Separation of the magnetic phases at the Neel point in the diluted spin-Peierls magnet CuGeO3

Article

关键词: LONG-RANGE ORDER;    UNIFORM-ANTIFERROMAGNETIC PHASES;    SINGLE-CRYSTAL CU1-XZNXGEO3;    SI-DOPED CUGEO3;    NEUTRON-SCATTERING;    COMPOUND CUGEO3;    TRANSITION;    ZN;    RESONANCE;    DIAGRAM;   

DOI  :  10.1103/PhysRevB.65.144427

来源: SCIE

【 摘 要 】

The impurity-induced antiferromagnetic ordering of the doped spin-Peierls magnet Cu1-xMgxGeO3 was studied by the electron-spin-resonance (ESR) technique. Crystals with x<4% demonstrate the coexistence of paramagnetic and antiferromagnetic ESR modes. This coexistence indicates the separation of a macroscopically uniform sample in the paramagnetic and antiferromagnetic phases. In the presence of long-range spin-Peierls order (at x=1.71%) the volume of the antiferromagnetic phase immediately below the Neel point T-N is smaller than the volume of the paramagnetic phase. In the presence of the short-range spin-Peierls order (x=2.88 and 3.2%) there are comparable volumes of two phases at T=T-N. The fraction of the antiferromagnetic phase increases with lowering temperature. In the absence of the spin-Peierls dimerization (at x=4.57%) the whole sample exhibits a transition into an antiferromagnetic state, and there is no phase separation. These results are explained by a consideration of clusters of staggered magnetization appearing near impurities within the singlet spin-Peierls matrix. Overlapping clusters form the antiferromagnetic phase, and isolated clusters contribute to the paramagnetic resonance signal.

【 授权许可】

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