High-field magnetic properties of the alternating ferro-antiferromagnetic spin-chain compound Cu${}_2$(OH)${}_3$Br

Abstract

We present comprehensive high magnetic field studies of the alternating weakly coupled ferro-antiferromagnetic (FM-AFM) spin-$1/2$ chain compound Cu${}_2$(OH)${}_3$Br, with the structure of the natural mineral botallackite. Our measurements reveal a broad magnetization plateau at about half of the saturation value, strongly suggesting that the FM chain sublattice becomes fully polarized, while the AFM chain sublattice remains barely magnetized, in magnetic fields at least up to $50$ T. We confirm a spin-reorientation transition for magnetic fields applied in the $a{c}^{\ast }$-plane, whose angular dependence is described in the framework of the mean-field theory. Employing high-field THz spectroscopy, we reveal a complex pattern of high-frequency spinon-magnon bound-state excitations. On the other hand, at lower frequencies we observe two modes of antiferromagnetic resonance, as a consequence of the long-range magnetic ordering. We demonstrate that applied magnetic field tends to suppress the long-range magnetic ordering; the temperature-field phase diagram of the phase transition is obtained for magnetic fields up to $14$ T for three principal directions ($a$, $b$, $c^{\ast }$).

10 pages, 8 figures

References in corpus (10)

• Quantum magnetism in the paratacamite family: towards an ideal kagome lattice
• Unusual ordered phases of highly frustrated magnets: a review
• Phase diagram of the Shastry-Sutherland Compound SrCu2(BO3)2 under extreme combined conditions of field and pressure
• Coexistence and interaction of spinons and magnons in an antiferromagnet with alternating antiferromagnetic and ferromagnetic quantum spin chains
• Phase diagram and spin Hamiltonian of weakly-coupled anisotropic S=1/2 chains in CuCl2*2((CD3)2SO)
• Specific Heat of the Kagome Antiferromagnet Herbertsmithite in High Magnetic Fields
• Multiferroic phases of the frustrated quantum spin-chain compound linarite
• First-principles characterization of the magnetic properties of Cu${}_2$(OH)${}_3$Br
• Coupled frustrated ferromagnetic and antiferromagnetic quantum spin chains in the quasi-one-dimensional mineral antlerite, Cu${}_3$SO${}_4$(OH)${}_4$
• Incommensurate and multiple-$\mathbf{q}$ magnetic misfit order in the frustrated quantum-spin-ladder material antlerite, Cu${}_3$SO${}_4$(OH)${}_4$