Static and dynamic magnetization control of extrinsic multiferroics by the converse magneto-photostrictive effect

In this work, photostrictive manipulations of static and dynamic magnetic properties are demonstrated in an extrinsic multiferroic composite. The photostriction is achieved with visible light in the blue region of the spectrum. The composites consist of 5 nm or 10 nm magnetostrictive Fe$_{81}$Ga$_{19}$ thin films coupled to a piezoelectric (011)-Pb(Mg$_{1/3}$Nb$_{2/3}$)O$_3$-Pb(Zr,Ti)O$_3$ substrate. Angular dependent magnetization reversals properties are largely enhanced or reduced under a converse magneto-photostrictive effect (CMPE). The CMPE strength is analysed with a novel coefficient named the converse magneto-photostrictive coupling coefficient. This coefficient is proposed as a general approach to analyse and to compare different extrinsic multiferroics under the converse magneto-photostrictive effect. Its thickness dependence reveals that the CMPE strength decreases with an increase of the Fe$_{81}$Ga$_{19}$ thickness. Experimental evidence for a control of dynamic magnetic properties under CMPE is then revealed by ferromagnetic resonance measurements. Resonant fields are shifted under CMPE, whereas their linewidths remain constant. Furthermore, resonant field shifts can be either positive or negative depending on the in-plane angle. The largest shift under CMPE of +5.7 % is obtained for the 5 nm sample. Our study shows that the CMPE provides an efficient approach for a control of not only the static but also the dynamic magnetic properties in extrinsic multiferroics.

the converse magneto-photostrictive effect.Its thickness dependence reveals that the CMPE strength decreases with an increase of the Fe 81 Ga 19 thickness.Experimental evidence for a control of dynamic magnetic properties under CMPE is then revealed by ferromagnetic resonance measurements.Resonant fields are shifted under CMPE, whereas their linewidths remain constant.Furthermore, resonant field shifts can be either positive or negative depending on the in-plane angle.The largest shift under CMPE of +5.7 % is obtained for the 5 nm sample.Our study shows that the CMPE provides an efficient approach for a control of not only the static but also the dynamic magnetic properties in extrinsic multiferroics.
The "digital world" has a large environmental cost and the predictions shows that it will be responsible for more than 20 % of the world's electricity consumption by 2030. 1,24][5][6] The strain control of magnetic anisotropy constitutes a keystone of the research area named magnetic straintronics, where strain-induced physical effects in solids are used to develop next-generation devices for energy-saving technologies including energy efficient information storage and sensor.9][10] ExMF simultaneously display two or more ferroic orders (eg.ferroelectric, ferromagnetic or/and ferroelastic), and their magnetic properties can be modified through strain. 11These are multi-functional materials with magnetostrictive and piezoelectric phases.The mechanism of strain driven magnetic properties in ExMF relies on the strain being transferred to the magnetostrictive phase and, in turn, induces inverse magnetostriction (the Villari effect 12 ), which translates into a change in magnetic properties.6][13][14][15][16][17][18][19][20][21][22][23][24] Strain can be introduced in the ExMF using a variety of stimuli, however, it is important that the strain is produced using an energy-efficient method in order to reduce environmental costs.
13][14][15][16][17][18][19][20]22 The magneto-electric coupling occurs when an applied electric field induces strain in the piezoelectric phase through the piezoelectric effect.In order to quantify the relative magnetization change upon applying an electric field, a converse magneto-electric coupling coefficient can be expressed as α CM E = µ 0 ∂M/∂E (in s.m −1 ), with µ 0 the vacuum permeability, M the magnetization and E the electric field. 13,18,20,25,266][27][28][29][30][31][32] A major objective of these studies was to understand driving mechanisms of the magneto-electric coupling phenomenon and to compare its efficiency in different materials.In general, previous studies have shown that electric field control of static and dynamic magnetic properties through strain is of interest in the context of energy saving technologies. 33However, large electric fields are required for this control and different mechanisms for strain control of magnetic properties would be of prime interest.
In ExMF, only a few studies focused on the optical control of ferromagnetic magnetization using the photostrictive effect and the understanding thereof. 21,23The photostrictive effect is the light-induced non-thermal dimension change of materials.The mechanism responsible for the phenomenon is different depending on the material.In ferroelectric materials, photostriction arises from a combination of photovoltaic and reverse piezoelectric effects and it is present in ExMF ferroelectric substrates. 34,35Response times of photostrictive effects in ferroelectrics are rather slow, from tenths of a second to minutes.This limitation originates from the slow building up of the photovoltage across the material in order to generate the strain.It was recently demonstrated that this limitation can be overcome by utilizing the faster microscale photovoltaic response and construction of local photostrictive strain. 36e change of magnetic properties under the photostrictive effect occurs when light induces strain in the piezoelectric phase through the photostrictive effect.The dimensional changes are transferred to the magnetostrictive phase and, in turn, induces inverse magnetostriction, which translates into a change in magnetic properties.The change of magnetic properties under the photostrictive effect defines the converse magneto-photostrictive effect (CMPE), which can be schematically written as (light/mechanical) × (mechanical/magnetic).
Two previous studies have shown that converse magneto-photostrictive effect does occur in ExMF. 21,23These studies revealed modifications of the thin films ferromagnetic magnetization reversal loops, under substrate illumination in Ni(11 nm)/BiFeO substrate.For the 5 nm and 10 nm FeGa thicknesses, the evolution of anisotropic properties is presented through the angular dependencies of the magnetization reversal (MRev) properties in the dark state, that is without illumination, and under a laser illumination.Then, a converse magneto-photostrictive (CMP) coupling coefficient, α λ CM P , is proposed.In order to determine its anisotropic characteristics and thickness dependence, angular dependencies, signs and magnitudes of α λ CM P are probed for the 5 nm and 10 nm FeGa thicknesses.Finally, for the 5 nm thick FeGa, a comparison between magneto-electric and magneto-photostrictive effects is made through the analysis of the angular dependencies of α λ CM P and α CM E .The thickness dependence of the maximum value of the α λ CM P is established.Finally, using ferromagnetic resonance measurements, experimental evidence for the control of the dynamic magnetic properties by CMPE is revealed.
In this study, a rhombohedral PMN-PZT single crystal is chosen as a substrate since it is a relaxor-PbTiO 3 (relaxor-PT) based ferroelectric.It is used for its excellent piezoelectric properties. 37,38In particular, (011) PMN-PZT demonstrates a large in-plane anisotropic piezostrain. 38,391][42][43] In addition, the FeGa/PMN-PZT heterostructure studied in this manuscript was shown to exhibit a large magneto-electric coupling coefficient. 26Consequently, if an optical stimulus would provide non-negligible strain through the PMN-PZT photostriction, it is likely to lead to a non-negligible control of FeGa magnetic properties through the inverse magnetostrictive effects.The samples were prepared by depositing the magnetostrictive FeGa thin films onto the PMN-PZT substrates, using radio-frequency magnetron sputtering.The growth was carried out under an in-plane magnetic field H dep = 2.4 kA.m −1 along the [100] direction of the PMN-PZT substrate.In the rest of this manuscript, ϕ is the angle between the applied magnetic field H and the [100] direction of the PMN-PZT substrate.Static magnetic measurements at room temperature were done using the magneto-optic Kerr effect (MOKE).The CMPE control of static magnetic properties was studied by illuminating the samples with an intensity I 1 of 0.6 W.cm −2 from a 410 nm laser diode.Dynamic measurements were obtained using an electron paramagnetic resonance spectrometer operating at X-band (9.3 GHz).For dynamic measurements, the CMPE was studied by illuminating the samples with the laser diode (the one previously described in the Static magnetic measurements) and it was also studied by illuminating the samples with a LED.The LED wavelength is 405 nm and the intensity of the LED illumination is 7 W.cm −2 .MOKE measurements could not be performed with the LED due to space restrictions in the experimental set-up.

Results
Magnetization reversals in the dark state and under illumination.for the 5 nm and 10 nm samples are modified under laser illumination.These modifications did not evolve with time (see Figure S3 of the supplemental materials for more information).Also, the maximum increase in sample temperature due to the illumination was (0.6 ± 0.1)K during measurements (see Figure S4 of the supplemental materials for more information).
It should be noted that we previously showed that such a limited temperature increase does not significantly modify the magnetization reversal of FeGa thin films grown on PMN-PZT substrates. 26The light-induced changes shown in Figures 1 (a) and (b) reveal a non-thermal and stable control of the FeGa magnetic properties through the PMN-PZT photostriction.
4][15][16][17][18][19][20]22 Under CMPE, both samples reveal a decrease in the M-H loop area for magnetic fields applied along ϕ = 0°but an increase in the M-H loop area along ϕ = 75°.It may be noted here that such an angular phenomenon due to illumination has not previously been reported in ExMF.A previous study on a Ni/PMN-PT heterostructure probed the lightinduced changes of MRev along two different axes but did not report such a MRev angulardependent property. 23Here, the observed FeGa/PMN-PZT CMPE is angular-dependent not only in magnitude but also "in sign" (in the sense of a decrease or increase in MRev characteristic properties).For both samples, the CMPE does not affect the normalized For both samples, the CMPE reduces the coercive field (H c ) along ϕ = 0°but increases H c along ϕ = 75°.
In order to further understand this angular-dependent CMPE, MRev angular dependencies were probed for both samples.In the dark state, and under CMPE, H c and M n R values have been obtained from each M-H loop as shown in Figure 1 (c)-(f).Probing these H c and M n R angular dependencies is of interest because they are related to magnetic anisotropic properties.In previous studies on FeGa thin films, it was shown that FeGa anisotropy configurations involve an uniaxial anisotropy (UA), a cubic anisotropy (CA) and a random anisotropy (RA). 26,42,43An UA was found to be driven by H dep .The UA results in the presence of H c and M n R maxima (minima) along a single axis named the easy axis (the hard axis).The CA was found to originate from a (110) FeGa preferred orientation.The CA results in the presence of H c and M n R maxima (minima) along two distinct easy (hard) axes.The RA arises from the polycristalline nature as the FeGa (110) orientation is only preferential.The RA does not result in H c and M n R extrema.FeGa thin films crystallographic textures have been shown to be thickness-dependent, and hence their anisotropic configurations too. 42In the study presented here, probing H c and M n R angular dependencies under CMPE for two different FeGa thicknesses should provide a way to assess FeGa anisotropy modifications under CMPE.
Here, for both thicknesses, H c and M n R angular dependencies exhibit global (local) maxima lying along the 0°(90°) axis corresponding to the global (local) easy axis, as shown in Figure 1.The presence of these maxima of different magnitudes reveals the presence of UA and CA. 43,44For both thicknesses, the presence of two hard axes on each side of the easy axes is also shown by the angular-dependent study.Indeed, H c and M n R angular dependencies of the 5 nm ( 10 Converse magneto-photostrictive coupling coefficient : definition as estimated from M (H) data in Figure 1 for the Ta(10 nm)/FeGa(5 nm (a); 10 nm (b))/PMN-PZT samples.
As previously introduced, the converse magnetoelectric coupling coefficient α CM E (expressed in s.m −1 ) was defined to quantify the electric-field-induced variation in the magnetic properties. 35,45This coefficient was calculated as α CM E (H) = µ 0 ∆M (H)/∆E, with ∆M (H), the change in magnetization at a field H under a change of electric field ∆E. 13,18,20,25,26Thus, it represents the variation of the magnetization under an applied electric field.This coefficient allows an evaluation of the electric stimulus efficiency, provides a way to correlate this efficiency with materials fundamental properties, and provides a convenient approach for comparing different materials.It has proven to be interesting and is now widely used for ExMF.In a similar way, we propose here to assess the light-induced variation of the magnetic properties through photostriction with a converse magneto-photostrictive coupling coefficient, α λ CM P = µ 0 ∂M/∂I (expressed in s.A −1 ) with I the light intensity.The magneto-photostrictive coefficient α λ CM P is calculated by : with ∆M (H), the change in magnetization at a field H under a change of light intensity ∆I at a wavelength λ.In our experimental work, α 410 CM P (H) can be determined with I 1 = 0.6 W.cm −2 and I 0 = 0.The relative change in magnetization is directly computed from the measured MRev loops in the dark state and under CMPE.FeGa thin films studied here have a saturation magnetization µ 0 M s = 1.15 T. 42 Thus, the α 410 nm CM P values can be calculated.
Figure 2 shows α 410 nm CM P (H) at 0°and 75°for the two FeGa thicknesses.These were determined using the M-H loops shown in Figure 1.Significant dependencies of α 410 nm CM P on the external magnetic field H are observed.For both thicknesses and for both angles, α 410 nm CM P (H) exhibits two extrema of opposite signs.The first (second) extremum, α ↓ ext (α ↑ ext ), occurs when H decreases (increases) as shown in Figure 2 (a) and (b).Over the full angular range, α ↓ ext (ϕ) and α ↑ ext (ϕ) are of the same magnitude within experimental uncertainty but of opposite sign as shown in Figure 3 (a) and (b).This is a consequence of M-H loops symmetry.α ↓ ext and α ↑ ext angular dependencies exhibit extrema along easy and hard axes.The extrema magnitudes are thickness-dependent.
Angular dependence of converse magneto-photostrictive coupling coefficient maxima.In order to further understand the CMPE through the use of α 410 nm CM P , let us first define the maximum value of the α 410 nm CM P (H) for a given angle ϕ as : The magnitude of the α 410 nm CM P,max angular dependence is proportional to the angular-dependent maximum change in magnetization inferred by the illumination as stated by Equation 1 (as long as the illumination is not angular-dependent).For both thicknesses, α 410 nm CM P,max extrema values are consistently present in the vicinity of the global easy and hard axes as shown in  α 410 nm CM P,max angular dependencies are thickness-dependent not only in shapes but also in magnitudes as shown in Figure 3 and in Table 1.It can be understood since the FeGa thin films magnetostrictive coefficient was found to decrease when the thickness increases 42 and a thickness-dependent dark state FeGa anisotropy configuration is present.About magnitudes, considering that an Fega thin film magnetization of 1.15 T is fully reversed due to an illumination of 0.6 W.cm −2 , the greatest α 410 nm CM P for FeGa thin films can be found from Equation 1 as 38×10 −5 s.A −1 .Relatively to this potential value, the greatest α 410 nm CM P,max obtained here are significant, indicating the CMPE efficiency for the ExMF examined in our study.This efficiency is also indicated by the maximum change of magnetization as shown in Table 1.
With respect to efficiency, for an ExMF it would be of interest to compare the angulardependent maximum change in magnetization inferred by different stimuli.In deed, as long as both stimuli are kept constant, α λ CM P and α CM E angular-dependent shapes are respectively equal to the shapes of angular-dependent maximum change in magnetization inferred by both stimuli.The α CM E angular dependence under an electric field (E) of 6.5 kV.cm −1 in the dark state and for the 5 nm sample was previously reported. 26It is shown in Figure 3 (c).Its shape is similar to that of the α 410 nm CM P,max angular dependence shape.Such a similarity indicates comparable anisotropy modifications at stake under CMPE and CME.To compare the efficiency of both stimuli, the change of magnetization under CME and CMPE are given : a maximum (relative) change of magnetization of 0.87 ± 0.02 T (76%) is obtained under CMPE, and a maximum (relative) change of magnetization of 0.94 ± 0.02 T (82%) is obtained under CME.These values are an indication of the efficiency for both converse effects (i.e. both stimuli).
Experimental evidence for a control of the ferromagnetic resonance field by CMPE.Using Ferromagnetic Resonance (FMR), we probed the dynamic control of magnetization on the 5 nm and 10 nm FeGa thin films illuminated with an intensity of 7 W.cm −2 from a 405 nm LED.It should be noted here that the LED could not be used for static measurements due to space restrictions within the MOKE apparatus.Figure 4 (a) shows Ferromagnetic resonance (FMR) spectra obtained in the dark state and measured with the dc external magnetic field applied along ϕ = 0°(while the magnetic component of the microwave field was perpendicular to the dc field).It reveals a FMR lineshape with the resonance field (the external magnetic field at which the power absorption spectrum dI/dH crosses zero, i.e. maximum power absorption) at 87.5 kA.m −1 (63.7 kA.m −1 ) for the 5 nm (10 nm) thick FeGa.
For both thicknesses, no significant modifications of the FMR spectra were observed under 0.6 W.cm −2 illumination with the 410 nm laser diode.However, significant modifications of the FMR signal were obtained under CMPE with the 7 W.cm −2 LED illumination at 405 nm as shown in Figure 4   To further understand the angular dependence of FeGa dynamic properties modifications under CMPE, systematic FMR angular dependent studies were performed.For both thicknesses, angular dependencies of resonant field shifts under CMPE (∆H CM P E res ) exhibit extrema along global easy and hard axes as shown in Figure 5. Extrema are positive in the vicinity of the global easy axis but negative in the vicinity of the global hard axis as shown in Figure 5 (c) and (d).It shows that significant resonant field shifts are achieved and they are prominent in the vicinity of their anisotropy axes.Resonant field shifts are known to occur in ExMF under electric field. 46As a matter of comparison with our results, electrical field induced positive and negative shifts of the resonance field as a function of the in-plane azimutal angle were previously observed in FeGa/PMN-PT heterostructures. 47These shifts were shown to arise from electrical field induced modifications of FeGa anisotropy.In the study presented here, resonant field shifts of different signs are shown to be induced not by an electrical field but by an illumination.
Under CMPE with the LED illumination, the maximum value of ∆H CM P E res is +5.0 kA.m −1 (2.5 kA.m −1 ) for the 5 nm (10 nm) thick sample.It represents a 5.7% (4.0%) increase of the resonant field under CMPE for the thinner (thicker) sample.It confirms a CMPE decrease with increasing FeGa thickness, as determined by the static measurements.FeGa FMR linewidths, which is a critical parameter for microwave magnetic materials, are not modified by the CMPE.
It should be noted here that the temperature increase due to the LED illumination during FMR measurements was measured and found to be under 6 K (see Figure S5 of the supplemental information).In principle, the magnetization of a ferromagnet decreases because of the heating and this thermal effect results in a positive shift of a resonance field.
Here, the presence of a negative ∆H CM P E res indicates that the driving mechanism for this shift is not related to the magnetization decrease due to heating.Furthermore, in the dark state, a study of the thermal dependence of the resonance field position revealed a shift of +0.04 kA.m −1 .K −1 along ϕ = 0°.Given that thermal dependence, the maximum induced resonant field shift due to a 6K heating is calculated to be +0.24kA.m −1 , which is very little as compared to resonant field shifts under illumination observed in our study.Also, resonant field shifts and temperature changes do not exhibit similar time dependence (see Figure S5 of the supplemental information).The observed light-induced shift is thus mainly attributed to the CMPE and results presented here are experimental evidences for the control of dynamic properties by CMPE.

Discussion
In summary, our study reveals that not only that static but also dynamic magnetic properties of an extrinsic multiferroic can be modified by CMPE under visible light.About static properties, magnetization reversals of 5 nm and 10 nm FeGa thin films on PMN-PZT substrates are shown to be modified by CMPE.The angular dependent study shows that M-H loops area, coercive fields and remanent magnetizations are enhanced or reduced under CMPE according to the direction of the applied field.A converse magneto-photostrictive coefficient, α λ CM P , is defined in this manuscript.It provides a general approach to analyse and to compare different ExMF under CMPE.α 410 nm CM P angular-dependent shapes and magnitudes are thickness-dependent but its magnitude always presents maxima in the vicinity of global easy axes.When compared, the angular dependence for the α 410nm CM P and for the converse magneto-electric coefficient are similar in shape.
We reveal that dynamic properties of magnetization probed by FMR are shown to be significantly modified under CMPE with visible light.Resonance fields are shifted under CMPE whereas their linewidths remain constant.Furthermore, these shifts are either positive or negative as a function of the in-plane angle, with maxima along global easy axes.
The largest shift of 5.7% is obtained for the thinnest sample along the global easy axis.
Our study demonstrates that the CMPE constitutes an alternative and complementary approach to the use of electric fields for a control of static and dynamic magnetic properties in multiferroics.In general, the work presented here provides an experimental foundation for a better understanding of ExMF materials and properties.The CMPE dependence on the illumination characteristics (intensity, wavelength, polarization) should be of interest for a further understanding of the light-matter interaction encountered here, for the FeGa/PMN-PZT system and for other ExMF.Furthermore, to reduce slow response times observed in our study, utilizing the faster microscale photovoltaic response and construction of local photostrictive strain should also be of interest.
In general, the work presented here provides a path towards understanding the light-induced magnetization changes.It shines a new light on use of photostriction to control not only static but also dynamic magnetic properties.These remote controls present a potential to be used in wireless and energy efficient approaches to control magnetic properties and tunable RF/microwave devices.W of deposition power and about 10 sccm argon flow rate.The stack was capped in situ with a 10 nm-thick Ta layer to protect the FeGa layer against oxidation.The growth was carried out under an in-plane magnetic field H dep = 2.4 kA.m −1 along the [100] direction of the PMN-PZT substrate.Further information on the poling procedure, growth conditions, growth preparations can be found in previous publications. 26,42atic magnetic measurements : magnetic measurements at room temperature were determined using the magneto-optic Kerr effect (MOKE) in a wide-field Kerr microscope from Evico Magnetics. 49In order to improve the signal-to-noise ratio, any MRev loop presented in this manuscript results from the average of 5 MRev loops acquired during 150 s.The CMPE control of static magnetic properties was studied by illuminating the samples with an intensity I 1 of 0.6 W.cm −2 from a 410 nm laser diode.The laser spot size is (570×1776) µm 2 (FWHM) and the incident angle of the laser beam on the sample surface is 20°.The samples were illuminated on the backside (i.e. the substrate side).For further information, a scheme of the experimental setup can be found in the supplementary information (see Figure S1).When the substrate was illuminated, the magnetic measurements were offset by a delay time of 60 s.Increasing the delay time did not change the results of the static magnetic measurements presented in this manuscript.The temperature was probed during measurements using an infrared pyrometer.
Dynamic magnetic measurements: an Elesxys 500 Bruker electron paramagnetic resonance spectrometer operating at X-band (9.3 GHz) was used to characterize the microwave performance of FeGa /PMN-PZT heterostructures.For dynamic measurements, the CMPE was studied by illuminating the samples with the laser diode (the one previously described in the Static magnetic measurements) and it was also studied by illuminating the samples with a LED.The LED wavelength is 405 nm and the intensity of the LED illumination is 7 W.cm −2 .The incident angle of the beam on the sample surface is 0°(i.e.along the surface normal).The samples were illuminated on the backside (i.e. the substrate side).When the substrate was illuminated, the magnetic measurements were offset by a delay time of 360 s.
Increasing the delay time did not change significantly the results of the dynamic magnetic measurements presented in this manuscript, as shown in the Figure S5 of the supplementary information.

Figure 1 :
Figure 1: (a) and (b) Zoomed hysteresis loops of the normalized magnetization reversal of the Ta(10 nm)/FeGa(5 nm and 10 nm)/PMN-PZT(0.3 mm), measured in-plane with the magnetic field H, respectively, parallel to [100] (ϕ = 0°) and ϕ = 75°, under CMPE (i.e.under illumination at 410 nm) and in the dark state (OFF).(For information: the entire M-H loops are presented in Figure S2 of the supplementary materials).(c) and (d) H c polar plots for both samples, under CMPE and in the dark state.(e) and (f) M n R polar plot for both samples, under CMPE and in the dark state.(g) and (h) ∆H c and ∆M n R for both samples, under CMPE and in the dark state.
Figure 1 (g) and (h).The largest M n R modification under CMPE, ∆M n R , is an increase of +0.25 (i.e. a 60% relative increase).It is obtained along the 5 nm global hard axis.For both thicknesses, ∆H c and ∆M n R negative values are observed with their minima always on

Figure 3 :
Figure 3: Angular dependencies of α ↓ ext and α ↑ ext for the (a) 5 nm and (b) 10 nm samples.Angular dependencies of α 410 nm CM P,max for the (c) 5 nm and (d) 10 nm samples.(c) The gray shaded area is an eye guide to indicate the α CM E,max values previously reported for a 5 nm FeGa sample (from 26 ).

Figure 3 (
Figure 3 (c) and (d).Maximum values are obtained in the vicinity of global easy axes.

Figure 4 :
Figure 4: (a) In-plane field-sweep FMR spectra for the 5 nm and 10 nm thick samples measured at 9.3 GHz along ϕ = 0°, in the dark state.(b) In-plane field-sweep FMR spectra for both samples measured at 9.3 GHz under CMPE induced by the LED illumination and in the dark state, along ϕ = 0°(top) and along ϕ = 75°(bottom).

Figure 5 :
Figure 5: Angular dependencies of |∆H CM P E res | for the 5 nm thick sample (a) and for the 10 nm thick sample (b).Angular dependencies of ∆H CM P E res for the 5 nm thick sample (c) and for the 10 nm thick sample (d).(Dashed lines indicate the hard axis angular positions, in the dark state, as shown in Figure 1, 2 and 3.)

Figure
Figure S2 (a) and (b) show the entire M-H loops which were zoomed to obtain Figure 1(a) and (b) of the manuscript.

Figure
Figure S3 shows the time evolution of M-H loops under sample illumination for the 10 nm FeGa sample at ϕ = 0 • .The illumination started at t = 0 s and a delay time of 45 s was set before starting the first M-H loop measurement.Each M-H loop took 150 s to be obtained.(In the manuscript, a given MH loop corresponds to the average of 5 MH loops.Thus, it took 5 × 150 s= 750 s to record each M-H loop presented in the manuscript).

Figure S 3 . 1 Figure
Figure S 3. Time evolution under sample illumination of the M-H loops for the 10 nm FeGa sample at ϕ = 0 • , zoomed in-between H = −1 kA.m −1 and 6 kA.m −1

Figure S 4 .
Figure S 4. Time evolution of temperature changes probed at the sample surface under laser illumination.

Figure
Figure S5 shows the time evolution of the temperature and of the resonance field for the 5 nm sample along ϕ = 0 • .The LED illumination began at t=125s (i.e.LED ON) and finished at t=1836s (i.e.LED OFF).

Figure S 5 .
Figure S 5. Time evolution of the temperature and of the resonance field for the 5 nm sample along ϕ = 0 • .
2323samples.However, CMPE key properties remain largely unexplored in ExMF.In particular, CMPE anisotropic properties in ExMF have not yet been studied, despite the im- 3  21and in Ni(11 nm)/PMN-

Table 1 :
Thickness dependence of the largest converse magneto-photostrictive coupling coefficient maxima (Maximum of α 410 nm CM P,max ), of the largest change of magnetization change under CMPE (Maximum of µ 0 ∆M ) and of the largest relative change of magnetization under CMPE (Maximum of ∆M M ).