Soliton-Mediated Magnetic Phase Transition in the Frustrated Antiferromagnet CsCoCl3
Hexagonal CsCoCl3 is a quasi-one-dimensional (1D) S=1/2 Ising antiferromagnet with intrachain interaction J=-75K. With decreasing temperature, a 3D magnetic transition occurs due to the weak antiferromagnetic interchain interaction as usual. However, a frustration effect due to triangular arrangement of the constituent magnetic chains in the c-plane gives rise to unusual successive phase transitions at TN1=21K and TN2=9K. The spin frustration model identifies the intermediate-temperature phase between TN1 and TN2 as a partially disordered (PD) phase in which 2/3 of magnetic chains order antiferromagnetically with each other, leaving the rest uncorrelated, and the low-temperature phase below TN2 as a ferrimagnetic (FR) phase in which all magnetic chains order in a collinear ferrimagnetic arrangement. While the model has succeeded in explaining the various experimental results, there remain several basic questions; Whether the PD phase is stable or not? How can 1/3 of chains behave paramagnetically? What happens at TN2? We have carried out magnetic resonance experiments (NMR, ESR) in order to solve these problems from a microscopic point of view.
KeywordsInternal Field Resonance Field Interchain Interaction Frustration Effect Magnetic Chain
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