Small-moment antiferromagnetic ordering

Magnetic Field vs Temperature phase diagram of La2Ni7 — Magnetic Field vs Temperature (H-T) phase diagram of La2Ni7, (a) for H||c, (b) for H⊥c constructed M(T ), M(H), ρ(T ), and ρ(H) data with T or H increasing. A, B, and C phases must be the same in the lowest field limit, the phases D, E, and F exist only at finite fields.

Scientific Achievement

Three zero-field magnetic transitions temperatures and six ordered phases found. These magnetically ordered phases are associated with small moments (∼0.12 μB/Ni) in the saturated state and small changes in entropy.

Significance and Impact

Rare example of a small moment itinerant antiferromagnet with multiple orderings and yet very little pressure dependence.

Research Details

Temperature and field dependent electrical resistivity and magnetization measurements identified six ordered phases and low field phase transitions at T1 = 61.0 ± 0.2K, T2 = 56.5 ± 0.2K, and T3 = 42.2 ± 0.2K.
The three specific heat anomalies found at these temperatures qualitatively have very small entropy changes associated with them.

R. A. Ribeiro , S. L. Bud’ko, L. Xiang , D. H. Ryan, and P. C. Canfield, "Small-moment antiferromagnetic ordering in single-crystalline La2Ni7," PRB 105, 014412 (2022).