Degeneracy of the 1/8 Plateau and Antiferromagnetic Phases in the Shastry-Sutherland Magnet TmB4

Abstract

The 1/8 fractional plateau phase (1/8-FPP) in Shastry-Sutherland Lattice (SSL) spin systems has been viewed an exemplar of emergence on an Archimedean lattice. Here we explore this phase in the Ising magnet TmB 4 using high-resolution specific heat (C) and magnetization (M) in the field-temperature plane. We show that the 1/8-FPP is smoothly connected to the antiferromagnetic (AF) phase on ramping the field from H = 0. Thus, the 1/8-FPP is not a distinct ground state of TmB 4 . The implication of these results for Heisenberg spins on the SSL is discussed.

Evolution of field-induced metastable phases in the Shastry-Sutherland lattice magnet TmB4

“…Our measurements, which extend to lower temperatures than those described in Refs. [17,36,39,47], show that in the downward sweep at T = 3.5 K, M ≈ 1/7M sat , for T ≈ 2 K, M ≈ 1/8M sat , and at progressively lower temperatures the plateau further diminishes [43]. For the upward sweep, the plateau is entirely absent for T < 2 K, as shown in Fig.…”

“…Ruderman-Kittel-Kasuya-Yoshida) interactions, which can be parametrized to produce long-range ordered phases in both 1/2 and 1/8 plateaus [18][19][20][21][22][23][24][25][26][27][28]. Experiments are usually interpreted in terms of simple structures implied by idealized values of the plateau magnetization (e.g., [31,36]). However, we show that historydependent values of M occur within the ∼1/8 plateau, and that different structures with different periodicities occur in and between the plateaus, and may coexist in history-dependent proportions (Figs.…”

“…A connection between the magnetization plateaus of TmB 4 and the quantum Hall effect was made via a theory mapping a spin system to a two-dimensional electron gas [31][32][33]. Although this theory may be relevant to the well-known S = 1/2 Shastry-Sutherland lattice compound SrCu 2 (BO 3 ) 2 [34,35], hysteresis effects [17], temperature-dependent values of the magnetization in the plateau [29], and thermodynamic measurements [36] show that the 1/8 plateau in TmB 4 is metastable, so such a theory is probably not relevant to TmB 4 . Similar phase diagrams with fractional plateaus and multiple ordered phases are observed for other members of the series of RB 4 , with R = Nd, Tb, Dy, Ho, Er [16,[37][38][39][40][41][42].…”

Insulator-metal transition and quasi-flat-band of Shastry–Sutherland lattice

“…9,10 While for small α, the Néel states will become the ground state since a SSL tends to degenerate to square lattice. Between the dimer-singlet state and the Néel state, many intermediate phases [26][27][28][29][30] and the magnetization plateaus [31][32][33][34] have also been reported.…”

Magnetic Phase Diagram of Geometrically Frustrated Magnetic System ErB4 under High Pressure

“…Magnetic systems with geometrically frustrated interactions have attracted widespread interest in the last years due to discoveries of various new types of complex quantum ground states [1]. The interest in such systems, in particular, is related also with magnetization (m) plateaus at fractional values of saturation magnetization (m sat ).…”