Competing interactions and anisotropic magnetoresistance in layered CeTe2
PhysRevB_62_11609.pdf 121 KB
Jung, Myoung Hwa
On a single crystal of CeTe2 with a layered tetragonal structure, we have studied the effect of magnetic field on magnetic susceptibility M/B, specific heat C, and electrical resistivity ρ. It is confirmed that this compound orders antiferromagnetically at TN=4.4 K, while ρ(T) shows no anomaly at TN but a sharp peak at Tρ=6.1 K. Below Tρ, M/B rises suddenly for B∥c, the easy magnetization axis, suggesting the onset of a short-range ferromagnetic order. At 2 K, M(B∥c) shows a metamagnetic transition at a small field of 0.06 T from the antiferromagnetic ground state to a field-induced ferromagnetic state. The peak in C(T) shifts from 4.3 K in zero field to 4.0 K in B∥C=0.1 T, and furthermore a shoulder appears at 4.3 K. With increasing magnetic field, the shoulder changes to a broadened maximum, which shifts towards higher temperatures. These observations indicate that the ferromagnetic interaction competes with the antiferromagnetic one even in zero field. A large negative magnetoresistance, MR=[ρ(B)-ρ(0)]/ρ(0), was observed in the vicinity of Tρ. For I∥c, the MR amounts to -25% at 3 T for B∥c, which is twice that for B⊥c. The large MR for I∥B∥c is a result of the increase of the c-axis conduction in the field-induced ferromagnetic alignment of Ce spins. However, the MR for I⊥c is essentially the same for B∥c and B⊥c, suggesting the confinement of carriers within the Te sheet sandwiched by the ferromagnetically coupled CeTe layers.
Physical Review B - Condensed Matter and Materials Physics
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Graduate School of Advanced Sciences of Matter