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arXiv · 2401.12098

SrCu(OH)$_3$Cl, an ideal isolated equilateral triangle spin $S$ = 1/2 model system

Sudip Pal·Petr Doležal·Scott A. Strøm·Sylvain Bertaina·Andrej Pustogow·Reinhard K. Kremer·Martin Dressel·Pascal Puphal
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Abstract

We have investigated the magnetic ground state properties of the quantum spin trimer compound strontium hydroxy copper chloride SrCu(OH)$_3$Cl using bulk magnetization, specific heat measurements, nuclear magnetic resonance (NMR), and electron spin resonance (ESR) spectroscopy. SrCu(OH)$_3$Cl consists of layers with isolated Cu$^{2+}$ triangles and hence provides an opportunity to understand the magnetic ground state of an isolated system of \textit{S} = 1/2 arranged on an equilateral triangle. Although magnetization measurements do not exhibit a phase transition to a long-range ordered state down to \textit{T} = 2 K, they reveal the characteristic behavior of isolated trimers with an exchange of $J = 154$~K. The Curie-Weiss behavior changes around 50--80~K, as is also seen in the NMR spin-lattice relaxation rate. In zero magnetic field, our specific heat data establish a second-order phase transition to an antiferromagnetic ground state below \textit{T}= 1.2 K. We have drawn a magnetic field-temperature ($H$-$T$) phase diagram based on the specific heat measurements. The ESR data show divergence of the linewidth at lower temperatures, which precedes the phase transition to an antiferromagnetic long-range ordered state with unconventional critical exponents. The temperature variation of the $g$-factor further confirms the antiferromagnetic phase transition and reflects the underlying magneto-crystalline anisotropy of the compound.

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Sudip Pal, Petr Doležal, Scott A. Strøm, Sylvain Bertaina, Andrej Pustogow, Reinhard K. Kremer, Martin Dressel, Pascal Puphal. 2024-01-22. SrCu(OH)$_3$Cl, an ideal isolated equilateral triangle spin $S$ = 1/2 model system. https://doi.org/10.1103/physrevresearch.6.033027

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