Fig. 1: Spin chain and spin-Peierls (SP) phase of CuGeO3. | Nature Communications

Fig. 1: Spin chain and spin-Peierls (SP) phase of CuGeO3.

From: Triplon current generation in solids

Fig. 1

a Crystalline structure of CuGeO3. The Cu spin chains are shown as dotted lines. Spin-1/2 spin chains along the c-axis in CuGeO3 are formed by staking CuO2 chains. Jc and Jb denote the exchange interactions along the c and b-axis, respectively. b When temperature (T) falls down to the SP transition temperature TSP, CuGeO3 undergoes a SP transition. After the transition, the Cu spins dimerize and the ground state becomes a spin singlet state (\((\left|\uparrow \downarrow \right\rangle -\left|\downarrow \uparrow \right\rangle )/\sqrt{2}\) with S = 0). Elementary excitation in the SP phase is a triplon with S = 1. c Schematic band structure of triplon in CuGeO319,21. Three triplet states (\(\left|\downarrow \downarrow \right\rangle\), \((\left|\uparrow \downarrow \right\rangle +\left|\downarrow \uparrow \right\rangle )/\sqrt{2}\) and \(\left|\uparrow \uparrow \right\rangle\)) are threefold degenerated at zero fields. By applying a magnetic field (H), the Zeeman effect lift the degeneracy. d The ground state and excitation state of a ferromagnet. Elementary excitation is a magnon with S = 1. The magnons reduce the magnetization (M) along the magnetic field (H) as δSz. T dependence of magnetic susceptibility (χ) of CuGeO3 under an applied magnetic field of 1 T along the b-axis. The SP transition temperature TSP is illustrated as the arrow in the figure. f Magnetic field - temperature (H - T) spin phase diagram for the CuGeO3 sample obtained from the M(H) and χ(T) measurement results. The diamond symbols represent data taken from a previous study24. The dotted curves are guide for the eyes.

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