Extremely Weakly Interacting ΔSz=0 and Δ

Abstract

The plateau at 1=3 of the saturation magnetization M s in the metamagnet CeSb is accompanied by a state of ferromagnetic layers of spins in an up-up-down sequence. We measured M and the specific heat C in the plateau, spin wave analyses of which reveal two distinct branches of excitations. Those with ΔS z ¼ 1 as measured by M, coexist with a much larger population of ΔS z ¼ 0 excitations measured by C but invisible to M. The large density of ΔS z ¼ 0 excitations, their energy gap, and their seeming lack of interaction with ΔS z ¼ 1 excitations suggest an analogy with astrophysical dark matter. Additionally, in the middle of the plateau three sharp jumps in MðHÞ are seen, the size of which, 0.15%M s , is consistent with fractional quantization of magnetization per site in the down-spin layers.

Evolving Devil's Staircase Magnetization from Tunable Charge Density Waves in Nonsymmorphic Dirac Semimetals

“…For example, in CeSb, a pronounced plateau is observed at 1/3 of the saturation magnetization that remains flat for a wide field range. [ 54 ] On the other hand, in the low‐dimensional magnet NH 4 CuCl 3 , clean plateaus are found at 1/8 and 3/8 of the saturation magnetization. [ 42 ] In the case of CeSb 0.11 Te 1.90 , the first order derivative of M / M S (Figure , Supporting Information) suggests that the 1/3‐plateau is the most prominent one, as in CeSbSe.…”

“…[52,53] In particular, the "1/3 plateau" is observed when the layers are arranged in a ↑↑↓ configuration. Interestingly, two extremely weakly interacting spin-excitations with one of them having analogous properties to astrophysical "dark matter", have recently been observed within the "1/3 plateau" of CeSb, [54] showing the possibility of exploring new quantum states in the fractional magnetization plateaus. In the case of CeSb x Te 2−x−δ , we observe another signature of the spin-wave in the magnetic entropy (S m ), calculated from the heat capacity data (Figure S4c, Supporting Information).…”

Evolving Devil's staircase magnetization from tunable charge density waves in nonsymmorphic Dirac semimetals

“…In particular, the "1/3 plateau" is observed when the layers are arranged in a ↑↑↓ configuration. Interestingly, two extremely weakly interacting spin-excitations with one of them having analogous properties to astrophysical "dark matter", have recently been observed within the "1/3 plateau" of CeSb [54], showing the possibility of exploring new quantum states in the fractional magnetization plateaus. In the case of CeSb x Te 2−x−δ , we observe another signature of the spin-wave in the magnetic entropy (S m ), calculated from the heat capacity data (Figure S4c).…”