Thermodynamic properties of the anisotropic frustrated spin-chain compound linarite PbCuSO4(OH)2

Abstract

We present a comprehensive macroscopic thermodynamic study of the quasi-one-dimensional (1D) s = 1 2 frustrated spin-chain system linarite. Susceptibility, magnetization, specific heat, magnetocaloric effect, magnetostriction, and thermal-expansion measurements were performed to characterize the magnetic phase diagram. In particular, for magnetic fields along the b axis five different magnetic regions have been detected, some of them exhibiting short-range-order effects. The experimental magnetic entropy and magnetization are compared to a theoretical modelling of these quantities using DMRG and TMRG approaches. Within the framework of a purely 1D isotropic model Hamiltonian, only a qualitative agreement between theory and the experimental data can be achieved. Instead, it is demonstrated that a significant symmetric anisotropic exchange of about 10 % is necessary to account for the basic experimental observations, including the 3D saturation field, and which in turn might stabilize a triatic (three-magnon) multipolar phase.

Hyperfine and crystal field interactions in multiferroic HoCrO3

“…4(a). [38]. Based on optical absorption spectroscopy [30], magnetization and magnetic susceptibility [17], specific heat [39], elastic neutron diffraction [40] and inelastic neutron scattering (INS) [41] experiments five electronic Schottky levels were observed in HoCrO 3 with the fifth level being at ∼272 K (23.4 meV).…”

Dynamics of linarite: Observations of magnetic excitations

“…Unfortunately, for many of the candidates for exhibiting multipolar phases, the involved AFM magnetic couplings and thus the saturation field are quite large, making it difficult to probe the multipolar phases. In this respect, linarite, PbCuSO 4 (OH) 2 , is a promising spin-multipolar candidate as the Cu 2+ ions form a quasi-1D S = 1/2 spinchain along the crystallographic b-axis 17,[30][31][32][33] . The material crystallizes in a monoclinic space group P 2 1 /m with lattice parameters 31,32,34 (at 1.8 K) a = 9.682Å, b = 5.646Å, c = 4.683Å, and β = 102.65 • (Fig.…”

“…We have recently presented an extensive thermodynamic investigation of linarite, establishing a rich and detailed phase diagram along each of the principal directions 17,[31][32][33] . Below T N = 2.8 K linarite shows magnetic long range order at zero field.…”

Cs2NaAl1−xCrxF6: A family of compounds presenting magnetocaloric effect

“…As mentioned previously, adiabatic demagnetization of paramagnetic salts was the first method of magnetic refrigeration to reach temperatures significantly below 1 K. Although the 3 He- 4 He dilution refrigerator has replaced this technology in some devices, it nevertheless has the convenience of being a continuous refrigeration method, and paramagnetic refrigeration still has some advantages. A physical disadvantage of paramagnetic salts is their low thermal conductivity.…”

“…Magnetic refrigerators are promising devices based on the magnetocaloric effect (MCE), with applications including hydrogen liquefiers, high-speed computers, and superconducting quantum interference device (SQUID) cooling. Thus, the quest for new materials which exhibit the MCE and promise technological improvement has attracted much attention in recent years [1][2][3][4]. Two important thermodynamic quantities characterize the MCE: the temperature change in an adiabatic process ( T ad ) and the entropy change in an isothermal process ( S T ) upon magnetic field variation.…”