Low-temperature structural investigations of the frustrated quantum antiferromagnets Cs2CuCl(4-x)Br(x)

Abstract

Powder X-ray diffraction (PXRD) and single-crystal neutron scattering were used to study in detail the structural properties of the Cs2CuCl(4-x)Br(x) series, good realizations of layered triangular antiferromagnets. Detailed temperature-dependent PXRD reveal a pronounced anisotropy of the thermal expansion for the three different crystal directions of the orthorhombic structure without any structural phase transition down to 20 K. Remarkably, the anisotropy of the thermal expansion varies for different $x$, leading to distinct changes of the geometry of the local Cu environment as a function of temperature and composition. The refinement of the atomic positions confirms that for x=1 and 2, the Br atoms occupy distinct halogen sites in the [CuX4]-tetrahedra (X = Cl, Br). The precise structure data are used to calculate the magnetic exchange couplings using density functional methods for x=0. We observe a pronounced temperature dependence of the calculated magnetic exchange couplings, reflected in the strong sensitivity of the magnetic exchange couplings on structural details. These calculations are in good agreement with the experimentally established values for Cs2CuCl4 if one takes the low-temperature structure data as a starting point.

References in corpus (9)

• Experimental realization of a 2D fractional quantum spin liquid
• Observation of extended scattering continua characteristic of spin fractionalization in the 2D frustrated quantum magnet Cs2CuCl4 by neutron scattering
• Direct Measurement of the Spin Hamiltonian and Observation of Condensation of Magnons in the 2D Frustrated Quantum Magnet Cs2CuCl4
• Density Functional Application to Strongly Correlated Electron Systems
• Bose-Einstein Condensation of Magnons in Cs2CuCl4
• Multi-step approach to microscopic models for frustrated quantum magnets - the case of the natural mineral azurite
• Determination of effective microscopic models for the frustrated antiferromagnets Cs${}_2$CuCl${}_4$ and Cs${}_2$CuBr${}_4$ by density functional methods
• The stable phases of the Cs2CuCl4-xBrx mixed systems
• Distinct magnetic regimes through site-selective atom substitution in the frustrated quantum antiferromagnet Cs${}_2$CuCl${}_{4-x}$Br${}_x$

Cited by in corpus (5)

• Static and Dynamical Properties of the Spin-1/2 Equilateral Triangular-Lattice Antiferromagnet Ba${}_3$CoSb${}_2$O${}_9$
• Specific Heat Study of 1D and 2D Excitations in the Layered Frustrated Quantum Antiferromagnets Cs${}_2$CuCl${}_{4-x}$Br${}_x$
• Magnetic phase diagram of the triangular antiferromagnetic $C{s}_{2}CuC{l}_{4-x}B{r}_x$ mixed system
• Magneto-acoustic study near the quantum critical point of the frustrated quantum antiferromagnet Cs2CuCl4
• Magneto-structural properties of the layered quasi-2D triangular-lattice antiferromagnets Cs${}_2$CuCl${}_{4-x}$Br${}_x$ for $x$ = 0,1,2 and 4