Magnetic order in the quasi-one-dimensional Ising system RbCoCl3

Abstract

In RbCoCl 3 , the magnetic Co 2+ ions form weakly coupled Ising chains arranged on a triangular lattice. We have investigated the structure and magnetism in RbCoCl 3 by high-resolution x-ray diffraction and neutron scattering measurements on powder and single-crystal samples between 1.5 and 300 K. Upon cooling, the Co 2+ spins develop one-dimensional antiferromagnetic correlations along the chain axis (c axis) below 90 K. Below the first Néel temperature, T N1 = 28 K, a partial three-dimensional magnetic order sets in, with propagation vector k 1 = (1/3, 1/3, 1), the moments aligned along the c axis, and every third chain uncorrelated from its neighbors. Only below a second magnetic phase transition at T N2 = 13 K does the system achieve a fully ordered state, with two additional propagation vectors: k 2 = (0, 0, 1) establishes a "honeycomb" c-axis order, in which one third of the chains are subject to a strong effective mean field due to their neighbors whereas two thirds experience no net field, while k 3 = (1/2, 0, 1) governs a small, staggered, in-plane ordered moment. We conclude that RbCoCl 3 is an excellent material to study the physics of Ising chains in a wide variety of temperature-controlled environments, and our results build an important foundation for the accurate interpretation of the spin dynamics measured in each case.

Thermal Control of Spin Excitations in the Coupled Ising-Chain Material RbCoCl3

“…1(b)], frustrating the AF interchain interactions. They typically show two magnetic ordering transitions, which in RbCoCl 3 occur at T N 1 = 28 K and T N 2 = 12 K [21]. Thus, in contrast to CoNb 2 O 6 and BaCo 2 V 2 O 8 , different chains experience different environments at different temperatures.…”

“…Three high-quality RbCoCl 3 single crystals of total mass 7.6 g were grown by the Bridgman technique in a moving vertical furnace [21] ter LET (ISIS, UK) [24]. High-statistics data were collected with incident energy E i = 25 meV and (00L) perpendicular to the incident beam, at temperatures of 4, 18, and 35 K, i.e.…”

“…The partially disordered AF (PDAF) [18,34] state between T N 2 and T N 1 is characterized primarily by a decrease in FI interchain order [inset, Fig. 3(c)], while the staggered magnetization within each chain is also impacted [21] by thermally excited domain walls [35]. Although 3D order is lost above T N 1 , both susceptibility and diffuse scattering measurements [21] suggest that anomalously slow short-range correlations persist up to 60−80 K, and we will quantify this effect.…”

“…S5 [27]). Thus we quantify the extent to which interchain correlations remain important at T > T N 1 [21], i.e. close to but above the regime of finite long-range order.…”

Na$_5$Co$_{15.5}$Te$_6$O$_{36}$: an $S$ = 1/2 stacked Ising kagome antiferromagnet with a partially disordered ground state

“…It has been found that a composite geometry consisted of Ising chains in a two-dimensional array can inherit the excellent traits of both geometries. For * zhiyingzhao@fjirsm.ac.cn example, in the S = 1/2 stacked Ising triangular lattice antiferromagnets (TAFs) ACoX 3 (A = Rb, Cs; X = Cl, Br) and Ca 3 Co 2 O 6 , in which Ising Co chains are arranged in a triangular lattice, not only the domain-wall excitations of one-dimensional antiferromagnetic (AFM) Ising chain [26,27], but also the magnetization plateau and partially disordered state in triangular lattice [28][29][30][31] are observed. Besides, a disordered ground state is also found in Ba 3 Co 2 O 6 (CO 3 ) 0.7 due to its honeycomb structure [32,33].…”