Abstract
The metal–insulator transition (MIT) is a hallmark of strong correlation in solids^{1,2,3}. Quantum MITs at zero temperature have been observed in various systems tuned by either carrier doping or bandwidth^{1}. However, such transitions have rarely been induced by application of magnetic field, as normally the field scale is too small in comparison with the charge gap, whose size is a fraction of the Coulomb repulsion energy (∼1 eV). Here we report the discovery of a quantum MIT tuned by a field of ∼10 T, whose magnetoresistance exceeds 60,000%. In particular, our anisotropic magnetotransport measurements on the cubic insulator Nd_{2}Ir_{2}O_{7} (ref. 4) reveal that the insulating state can be suppressed by such a field to a zerotemperature quantum MIT, but only for fields near the [001] axis. The strong sensitivity to the field direction is remarkable for a cubic crystal, as is the fact that the MIT can be driven by such a small magnetic field, given the 45 meV gap energy^{5}, which is of order of 50 times the Zeeman energy for an Ir^{4+} spin. The systematic change in the MIT from continuous near zero field to first order under fields indicates the existence of a tricritical point proximate to the quantum MIT. We argue that these phenomena imply both strong correlation effects on the Ir electrons and an active role for the Nd spins.
Main
Nd_{2}Ir_{2}O_{7} belongs to the family of pyrochlore iridates^{6,7,8,9}, which have attracted a great deal of interest due to the combination of strong spin–orbit coupling and electronic correlations, which might hypothetically lead to various topological phases such as a topological Mott insulator, Weyl semimetal and axion insulator^{10,11,12,13,14}. In fact, recent experiments observed a chiral spin liquid state and quantum critical semimetallic state in Pr_{2}Ir_{2}O_{7} (refs 6,7,8), as well as continuous MITs and allin–allout (AIAO) ordering in Nd_{2}Ir_{2}O_{7} (ref. 4) and Eu_{2}Ir_{2}O_{7} (ref. 9).
Comprehensive surveys of the R_{2}Ir_{2}O_{7} compounds show a systematic decrease in the thermal MIT temperature with increasing ionic radius of R, reaching zero ‘between’ R = Nd and Pr, so that Nd_{2}Ir_{2}O_{7} is the closest insulator to the T = 0 quantum MIT. Indeed, Nd_{2}Ir_{2}O_{7} shows an apparently continuous MIT at T_{MI} ∼ 32 K, which is exceptionally low, especially relative to the gap E_{g} ∼ 45 meV observed experimentally^{5}, leading to the unusually large ratio E_{g}/T_{MI} ∼ 16. Recent neutron diffraction experiments suggest that in the lowtemperature phase both the Nd^{3+} and the Ir^{4+} moments have an AIAO magnetic structure, an Ising type order with all the moments pointing inward or outward from the centre of each tetrahedron (Fig. 1a)^{15}. What made this compound even more interesting is the recent proposal that this AIAO state may stabilize a Weyl semimetallic state^{10,11,12,13,14,16}, raising the question of the nature of the MIT proximate to such topological phenomena.
First we describe the key experimental observations to verify the MIT in our single crystals of Nd_{2}Ir_{2}O_{7}. The temperature dependence of the resistivity exhibits a MIT at T_{MI} ∼ 27 K under zero field (Fig. 1b). This transition temperature is slightly lower than the value ∼32 K observed in polycrystalline samples, most likely as a result of carrier doping by slight offstoichiometry within 1% (see Methods). Below T_{MI}, ρ(T) shows insulating (negative dρ/dT) behaviour (Fig. 1b inset). It is known that the AIAO magnetic order sets in concomitantly with the MIT (ref. 4). Indeed, exactly below T_{MI} ∼ 27 K, we found that the zerofieldcooled (ZFC) and fieldcooled (FC) magnetization bifurcate owing to the magnetic transition (Fig. 1c).
Now, we discuss our main discovery of the fieldinduced MIT and strongly anisotropic magnetoresistance. Figure 2a presents the angle dependence of the transverse magnetoresistance measured using pulsed high magnetic fields up to 50 T and a Nd_{2}Ir_{2}O_{7} single crystal with zerofield T_{MI} ∼ 20 K. Here we note that to reveal the field evolution of the continuous MIT peculiar to the Ir 5d bands, a single crystal with T_{MI} > 15 K is indispensable, as on cooling Nd moments freeze below 15 K (ref. 15). The field B was rotated within the (001) plane, perpendicularly to the current direction [], with the angle (θ) between the field and the [001] direction, as schematically shown in Fig. 2b inset. In this definition, θ = 35°, 55° and 90° correspond to the field direction of [112], [111] and [110] axes, respectively. In the field along these three directions, only a gradual decrease of the resistivity was found, revealing that the insulating state is stable up to 50 T. In sharp contrast, in the [001] direction, a rapid jump of the resistivity was observed at a critical field of B_{c} ∼ 10 T, above which the resistivity becomes nearly constant. The magnetoresistance [R(0) − R(B)]/R(B) amounts to ∼60,000%. This sharp resistivity drop characterizes the fieldinduced quantum phase transition to the highB semimetal state. This highfieldinduced semimetal state is also consistent with the temperaturedependent resistivity measurement, as shown in the inset of Fig. 2c. The narrow but clear hysteresis (∼1 T) seen at the critical field indicates that the transition is first order, despite the fact that the thermal transition at zero field is continuous.
To map out the interpolation between these limits, we show a selection of both the resistivity versus field and temperature at various temperatures and field in Fig. 2c, and its inset, respectively. Summarizing all the results, we construct a contour plot of the resistivity in the B–T phase diagram in Fig. 2d. We see that the enhanced resistivity is confined to a region of low B and T, and outside this region the resistivity is only weakly dependent on B and T. Thus, there are simply two phases: a resistive ordered antiferromagnetic state at low B and T, and a semimetallic paramagnetic state outside the ordered region (Fig. 2d). To characterize the thermal phase transition, we took the temperature derivative of the resistivity dρ/dT (Supplementary Information). For B = 0, 2 T, both dρ/dT taken on cooling and warming across T_{MI} nearly overlap each other, indicating a secondorder transition, whereas above 6 T they show clear hystereses across T_{MI} due to the firstorder character of the transition. This is consistent with the hysteresis seen in the fielddependent data shown in Fig. 2a and Supplementary Fig. 2. The MIT temperatures T_{MI} and critical fields B_{MI} are determined for both increasing (red diamond and circle) and decreasing (orange diamond and circle) sequences of temperature and field and are summarized in the phase diagram of Fig. 2d. This indicates that the tricritical point separating the second and firstorder transition exists between 2 and 6 T and approximately 18 K (Fig. 2d).
The strongly anisotropic character of the MIT can be seen from the fieldangle phase diagram made by the contour plot of the resistivity (Fig. 2b). The full angle dependence shows that the fieldinduced transition survives when the magnetic field is slightly tilted from the [001] direction towards [112], by up to θ < 15°, but the critical field increases rapidly with θ. The strong anisotropy is also evident in the isothermal magnetization measured at 2 K (Fig. 3a). In particular, a large hysteresis was observed for B [111], whereas M(B) is smooth for B [001] and [110]. The field derivative of the [111] magnetization curve reveals two distinct kinks, at approximately B_{c1} = 2.0 T and B_{c2} = 3.9 T (Fig. 3b). Naively, these are suggestive of Nd^{3+} spin flops (the Ir moments are negligibly small on this scale^{17}), which would arise in a classical ‘spinice’like Ising model^{18}. Such a model (using the singleion moment 2.4 μ_{B}/Nd) predicts saturation at 1.4, 1.2 and 0.98μ_{B}/Nd for B along [001], [111] and [110], consistent with 1.4, 1.2 and 1.1μ_{B}/Nd in experiment. However, the smoothness of the sweeps for the [001] and [110] field orientations, as well as the fact that the downsweep sequence shows no anomaly and reaches zero magnetization at zero field, are inconsistent with classical Ising spins.
We now discuss Nd_{2}Ir_{2}O_{7} theoretically, as a nearly critical Kondo lattice system with a particular hierarchy of energy scales. The largest energies are electronic, with bare local density approximation (LDA) bandwidths of the order of 0.5 eV for the j = 1/2like bands near the Fermi energy and Hubbard U of the order of 1–2 eV. The Kondo interaction between Nd and Ir spins is at a much lower energy scale, of the order of J_{K} ∼ 5–10 meV (see below). However, a large reduction of the effective bandwidth may occur due to correlations and proximity to the zerofield quantum MIT, as indicated by recent ARPES experiments^{19}. This opens a window unique to Nd_{2}Ir_{2}O_{7} where the Kondo coupling can influence the MIT.
We consider a model Hamiltonian H = H_{Ir} + H_{Nd}, where H_{Ir} includes all terms containing only Ir electrons, and H_{Nd} contains the Kondo interaction of overall strength J_{K} and the Zeeman term for Nd (see below). Details of the Hamiltonians are given in Supplementary Information.
The problem for J_{K} = B = 0 has been studied by meanfield theory^{12}, LDA + U (refs 10,20), dynamical mean field theory (DMFT; refs 20,21), and by field theory methods^{22}. All methods agree that with increasing U a nonmagnetic ground state gives way at U > U_{c} to an AIAO ordered state, which has a spectral gap for large enough U. The critical value U_{c} is of the order of 1 eV, and varies according to band parameters and approximation methods. For fixed U > U_{c}, the AIAO ordered state is favourable relative to the nonmagnetic state by a condensation energy that varies from E_{c} ∼ 100 meV to 15 meV depending on the method.
Now let us consider the role of Nd moments by turning on J_{k}. According to the crystal electric field scheme obtained experimentally, Nd^{3+} has a ‘dipolar–octupolar’ ground doublet, which can be represented by a vector Pauli spin operator τ_{i}, but which has an infinitely anisotropic gtensor: its moment lies exactly along its local 〈111〉 axis. Accordingly, the full form of H_{Nd} allowed by symmetry is where S_{i} is the Ir spin at site i, is a unit vector along the local 〈111〉 axis of Nd site j, and γ = 2.4μ_{B}, up to weaker direct exchange interactions between Nd spins. Note that the Kondo couplings, described by the matrix Λ (Supplementary Information) involve all components of the Nd spin, but we expect those involving the local z component τ^{z} dominate in most circumstances. An exception is in the evolution of the spin state from low to intermediate fields (∼10 T): there, the nonIsing interactions allow the Nd spins to rotate smoothly rather than flop, except when the field is along the [111] direction, which explains the main features of Fig. 3b, c (Supplementary Information).
To J_{K}linear order, we can treat the Kondo interaction in mean field, as effective selfconsistent static fields on the Nd and Ir spins. At zero field, this aligns the Nd spins into an AIAO state, and splits the Nd doublet by J_{K}^{∗}m_{Ir}. Using the measured splitting and m_{Ir} ≍ 0.1–0.2μ_{B} (ref. 15), we thereby determine J_{K} ≍ 5–10 meV. In turn, the ordered Nd spins induce a much larger effective field on the Ir electrons. This significantly reinforces the order, increases the condensation energy, and enhances the electronic gap, as observed^{5}. To check this proposition, we carried out Hartree–Fock calculations on an effective Kondo lattice model (Supplementary Information). Figure 4 shows results of AIAO staggered magnetization φ and the charge gap Δ. We indeed found the enhancement of the charge gap by the Kondo coupling.
We now consider the fieldtuned quantum MIT. This occurs for B ≥ 10 T, where M is nearly saturated: this implies the Zeeman term for Nd dominates over J_{K}, and hence the Nd spins are nearly fully polarized along their local z axes: in particular, when the field is at an angle θ < 15° from [001] they adopt a 2in–2out configuration, whereas for other angles they take a 3in–1out form. With the Nd spins polarized in the 2in–2out state, the condensation energy from the Kondo term is completely lost, which provides a mechanism to destroy the AF order. Indeed, we found a transition to a metallic or semimetallic state at low field for the [001] orientation, and not at all or at much higher fields along [110] or [111]. For the same model, we also found that the Kondo coupling J_{K} generally stabilizes the zerofield AIAO order even when it is absent for J_{K} = 0 (Fig. 4). The order of the quantum fieldtuned transition can be first or second order in the Hartree–Fock approximation, but a firstorder behaviour is likely when fluctuations beyond Hartree–Fock are included (Supplementary Information).
Finally, we discuss effects related to domain boundaries. We focus on the lowfield part of the anisotropic MR effect in Fig. 2a. Compared to the [001] direction, no marked MIT is seen for B [111]. Instead, the [111] MR shows complex hysteresis corresponding to changes in the Nd spin structure (Fig. 3c). The results (black line) in the initial upsweep process after ZFC show a gradual decrease with field and spikes sharply, reaching a minimum value at 3.4 T. In the consecutive field cycles, the resistance exhibits dips at ±3.9 T, where the derivative of M peaks, revealing the close correlations between the MR and magnetization. Notably, the MR after the initial sweep forms a smooth curve interrupted only near the spinflop transition by a temporary dip.
These observations can be understood in terms of two Ising domains of the AIAO order (Fig. 1a) which can be aligned by a [111] field^{23}. Without such alignment, the initial zerofield state has multidomains, and hence its lower resistivity may be attributed to more conductive domain walls. This is also consistent with the dip in the spinflop region of the hysteresis loop, where again domains are generated. Thus the Ising domain walls must be relatively conducting, as recently proposed theoretically^{24}.
It is useful to compare our result to the manganites^{1,2}, which provide a rare example of a fieldinduced MIT at a comparable field to the one discovered here in Nd_{2}Ir_{2}O_{7}. The two are quite distinct, as the former MIT is strongly first order at all temperatures, whereas in Nd_{2}Ir_{2}O_{7} the MIT appears continuous in zero field and transforms through a tricritical point to a firstorder transition as it is pushed to zero temperature in field. This may be connected to the phenomena of fluctuationdriven firstorder transitions in ferromagnetic quantum criticality^{25}, as the AIAO state, like the ferromagnetic state, has a zeromomentum order parameter. Yet Nd_{2}Ir_{2}O_{7} is unique in that the symmetry breaking and the MIT occur together, and in the prospect to observe topological phenomena in the transition region. Future studies should investigate the Hall effect as a probe of the latter.
Note added in proof: After submitting this manuscript, we became aware of a parallel work by Ueda et al. ^{26}, who observed a similar fieldinduced MIT. To avoid the influence of the freezing of Nd moments below 15 K on the MIT, a more stoichiometric single crystal with a higher MIT temperature (T_{MI} ∼ 20 K) was used in our study compared to the single crystal (T_{MI} ∼ 15 K) in ref. 26. The higherquality sample allowed us to find the existence of the possible tricritical points that are missed in the paper by Ueda and colleagues^{26}.
Methods
Sample preparation and characterization.
Several batches of single crystals of Nd_{2}Ir_{2}O_{7} have been grown by a potassium fluoride flux method^{27}. Powder and singlecrystal Xray diffraction analyses show a singlephase pyrochlore structure with lattice constant a = 10.386(3) Å. The MIT of pyrochlore iridates is known to be very sensitive to the stoichiometry and the transition temperature can be reduced rapidly with doping—as clarified, for example, for Eu_{2}Ir_{2}O_{7} (ref. 28). Thus, we performed a careful chemical analysis using electronprobe microanalysis (EPMA) and found a slight deviation from stoichiometry in the Ir/Nd ratio of approximately 1% for the single crystals with zerofield T_{MI} ∼ 27 K and of approximately 2% for the single crystals with with zerofield T_{MI} ∼ 20 K.
The magnetotransport was measured by a standard fourprobe method with the current path along the [] direction, and the magnetic field was always oriented perpendicular to the current direction. d.c. resistivity measurements in a d.c. magnetic field were carried out using a commercial system (PPMS, Quantum Design) which has a base temperature of 2 K and a maximum magnetic field of 14 T. For the field sweep measurements shown in Fig. 3c, the sample was first cooled down to 2 K under zero field and then the resistivity was measured by sweeping the magnetic field successively from 0 to 14 T, then from 14 to −14 T, and finally from −14 to 14 T. Electrical transport measurements up to 50 T in the pulsed high magnetic field were performed with frequency f = 100 kHz and electrical current I = 280 μA at the International Megagauss Laboratory at ISSP, the University of Tokyo. During the measurements, the electrical current was applied in the [] direction within the (001) plane, as schematically shown in Fig. 2b. The field dependence of the magnetization in a field up to 14 T (Fig. 3a) was measured using a commercial vibrating sample magnetometer system (PPMS, Quantum Design). The temperature dependence of the magnetization shown in Fig. 1c was measured using a commercial SQUID (superconducting quantum interference device) magnetometer (MPMS, Quantum Design) in zerofield cooling (ZFC) and field cooling (FC) procedures from 2 to 300 K.
Spinmodel analysis.
We analysed an effective spin model for the Nd moments, including all nearest neighbour interactions allowed by symmetry, Zeeman coupling to the external field, and a staggered Zeeman coupling representing the effect of Ir AIAO order. We studied the magnetization curve by treating the Nd spins as classical vectors and locally minimizing the energy, assuming a q = 0 spin configuration.
Meanfield theory.
The magnetic ground state and electronic structure of the Kondo lattice model were calculated by a selfconsistent meanfield method assuming q = 0 magnetic order. The electron–electron correlation was taken into account by the unrestricted Hartree–Fock method, and the localized spins were treated as classical vectors. We adopted a 32 × 32 × 32 superlattice of the foursite unit cell, with periodic boundary conditions for the calculation.
References
 1.
Imada, M., Fujimori, A. & Tokura, Y. Metal–insulator transition. Rev. Mod. Phys. 70, 1039–1263 (1998).
 2.
Kuwahara, H., Tomioka, Y., Asamitsu, A., Moritomo, Y. & Tokura, Y. A firstorder phase transition induced by a magnetic field. Science 270, 961–963 (1995).
 3.
Ramirez, A. P. Colossal magnetoresistance. J. Phys. Condens. Matter 9, 8171–8199 (2000).
 4.
Matsuhira, K., Wakeshima, M., Hinatsu, Y. & Takagi, S. Metal–insulator transition in pyrochlore oxides Ln_{2}Ir_{2}O_{7}. J. Phys. Soc. Jpn 80, 094701 (2011).
 5.
Ueda, K. et al. Variation of charge dynamics in the course of metal–insulator transition for pyrochloretype Nd_{2}Ir_{2}O_{7}. Phys. Rev. Lett. 109, 136402 (2012).
 6.
Nakatsuji, S. et al. Metalic Spinliquid behavior of the geometrically frustrated Kondo lattice Pr_{2}Ir_{2}O_{7}. Phys. Rev. Lett. 96, 087204 (2006).
 7.
Machida, Y., Nakatsuj, S., Onoda, S., Tayama, T. & Sakakibara, T. Timereversal symmetry breaking and spontaneous Hall effect without magnetic dipole order. Nature 463, 210–213 (2010).
 8.
Tokiwa, Y., Ishikawa, J. J., Nakatsuji, S. & Gegenwart, P. Quantum criticality in a metallic spin liquid. Nature Mater. 13, 356–359 (2014).
 9.
Sagayama, H. et al. Determination of longrange allinallout ordering of Ir^{4+} moments in a pyrochlore iridate Eu_{2}Ir_{2}O_{7} by resonant Xray diffraction. Phys. Rev. B 87, 100403 (2013).
 10.
Wan, X., Turner, A. M., Vishwanath, A. & Savrasov, S. Y. Topological semimetal and Fermiarc surface states in the electronic structure of pyrochlore iridates. Phys. Rev. B 83, 205201 (2011).
 11.
Pesin, D. & Balents, L. Mott physics and band topology in materials with strong spin–orbit interaction. Nature Phys. 6, 376–381 (2010).
 12.
WitczakKrempa, W. & Kim, Y. B. Topological and magnetic phases of interacting electrons in the pyrochlore iridates. Phys. Rev. B 85, 045124 (2012).
 13.
Yang, B. J. & Nagaosa, N. Emergent topological phenomena in thin films of pyrochlore iridates. Phys. Rev. Lett. 112, 246402 (2014).
 14.
WitczakKrempa, W., Go, A. & Kim, Y. B. Pyrochlore electrons under pressure, heat, and field: Shedding light on the iridates. Phys. Rev. B 87, 155101 (2013).
 15.
Tomiyasu, K. et al. Emergence of magnetic longrange order in frustrated pyrochlore Nd_{2}Ir_{2}O_{7} with metal–insulator transition. J. Phys. Soc. Jpn 81, 034709 (2012).
 16.
WitczakKrempa, W., Chen, G., Kim, Y. B. & Balents, L. Correlated quantum phenomena in the strong spin–orbit regime. Annu. Rev. Condens. Matter Phys. 5, 57–82 (2014).
 17.
Shapiro, M. C. et al. Structure and magnetic properties of the pyrochlore iridate Y_{2}Ir_{2}O_{7}. Phys. Rev B 85, 214434 (2012).
 18.
Sakakibara, T., Tayama, T., Hiroi, Z., Matsuhira, K. & Takagi, S. Observation of a Liquidgastype transition in the pyrochlore spin ice compound Dy_{2}Ti_{2}O_{7} in a magnetic field. Phys. Rev. Lett. 90, 207205 (2003).
 19.
Kondo, T. et al. Quadratic Fermi Node in a 3D strongly correlated semimetal. Preprint at http://arXiv.org/abs/1510.07977 (2015).
 20.
Zhang, H., Haule, K. & Vanderbilt, D. Metal–insulator transition and topological properties of pyrochlore iridates. Preprint at http://arXiv.org/abs/1505.01203 (2015).
 21.
Shinaoka, H., Shintaro, H., Troyer, M. & Werner, P. Phase diagram of pyrochlore iridates: Allin/allout magnetic ordering and nonFermi liquid properties. Phys. Rev. Lett. 115, 156401 (2015).
 22.
Savary, L., Moon, E. G. & Balents, L. New Type of quantum criticality in the pyrochlore iridates. Phys. Rev X 4, 041027 (2014).
 23.
Arima, T. TimeReversal symmetry breaking and consequent physical responses induced by allinallout type magnetic order on the pyrochlore lattice. J. Phys. Soc. Jpn 82, 013705 (2013).
 24.
Yamaji, Y. & Imada, M. Metallic interface emerging at magnetic domain wall of antiferromagnetic insulator: Fate of extinct Weyl electrons. Phys. Rev. X 4, 021035 (2014).
 25.
Brando, M., Belitz, D., Grosche, F. M. & Kirkpatrick, T. R. Metallic quantum ferromagnets. Preprint at http://arXiv.org/abs/1502.02898 (2015).
 26.
Ueda, K. et al. Magnetic fieldinduced Insulatorsemimetal transition in a pyrochlore Nd_{2}Ir_{2}O_{7}. Phys. Rev. Lett. 115, 056402 (2015).
 27.
Millican, J. N. et al. Crystal growth and structure of R_{2}Ir_{2}O_{7} (R = Pr, Eu) using molten KF. Mater. Res. Bull. 42, 928–934 (2007).
 28.
Ishikawa, J. J., O’Farrell, E. C. T. & Nakatsuji, S. Continuous transition between antiferromagnetic insulator and paramagnetic metal in the pyrochlore iridate Eu_{2}Ir_{2}O_{7}. Phys. Rev. B 85, 245109 (2012).
Acknowledgements
We thank A. Matsuo for technical assistance, and K. Behnia and A. Nevidomskyy for useful discussions. This work has been supported in part by GrantsinAid for Scientific Research (No. 25707030), Program for Advancing Strategic International Networks to Accelerate the Circulation of Talented Researchers (No. R2604) from the Japanese Society for the Promotion of Science and PRESTO of JST, and GrantinAid for Scientific Research on Innovative Areas (15H05882, 15H05883). L.B. was supported by the DOE Office of Basic Energy Sciences, DEFG0208ER46524. H.I. was supported by JSPS Postdoctoral Fellowships for Research Abroad. T.H.H. was supported by a KITP Graduate Fellowship and DOE Office of Basic Energy Sciences, DESC0010526.
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Affiliations
Institute for Solid State Physics (ISSP), University of Tokyo, Kashiwa 2778581, Japan
 Zhaoming Tian
 , Yoshimitsu Kohama
 , Takahiro Tomita
 , Jun J. Ishikawa
 , Koichi Kindo
 & Satoru Nakatsuji
Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106, USA
 Hiroaki Ishizuka
 , Timothy H. Hsieh
 & Leon Balents
Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
 Timothy H. Hsieh
PRESTO, Japan Science and Technology Agency (JST), 418 Honcho Kawaguchi Saitama 3320012, Japan
 Satoru Nakatsuji
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Contributions
S.N. planned the experimental project. Z.T., J.J.I. and S.N. prepared single crystals. Z.T., Y.K., T.T. and K.K. performed highfield measurements. L.B. planned the theoretical project. H.I., T.H.H. and L.B. performed theoretical calculations. Z.T., T.T., L.B. and S.N. wrote the paper. T.H.H. and H.I. wrote the theory in the Supplementary Information. All authors discussed the results and commented on the manuscript.
Competing interests
The authors declare no competing financial interests.
Corresponding authors
Correspondence to Leon Balents or Satoru Nakatsuji.
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