Coupled frustrated ferromagnetic and antiferromagnetic quantum spin chains in the quasi-one-dimensional mineral antlerite Cu3SO4 (OH) 4

Abstract

Magnetic frustration, the competition among exchange interactions, often leads to novel magnetic ground states with unique physical properties which can hinge on details of interactions that are otherwise difficult to observe. Such states are particularly interesting when it is possible to tune the balance among the interactions to access multiple types of magnetic order. We present antlerite Cu 3 SO 4 (OH) 4 as a potential platform for tuning frustration. Contrary to previous reports, the low-temperature magnetic state of its three-leg zigzag ladders is a quasi-one-dimensional analog of the magnetic state recently proposed to exhibit spinon-magnon mixing in botallackite. Density functional theory calculations indicate that antlerite's magnetic ground state is exquisitely sensitive to fine details of the atomic positions, with each chain independently on the cusp of a phase transition, indicating an excellent potential for tunability.

Incommensurate and multiple- q magnetic misfit order in the frustrated quantum spin ladder material antlerite Cu3SO4(OH)4Kulbakov1, Sadrollahi2, Rasch3 et al. 2022Phys. Rev. BSelf Cite2000View full textAdd to dashboardCite

“…Below 1.6 K the specific heat data vary as T 2.5 , with a slight upward deviation below 0.5 K that may be associated with nuclear magnetism. As previously reported [7], no further phase transitions are observed down to 0.35 K.…”

“…The small and slightly positive Curie-Weiss temperatures indicate a balance between antiferromagnetic and ferromagnetic exchange pathways, with a slight edge for ferromagnetism. DFT calculations and the low-temperature magnetic structure indeed suggest ferromagnetic interactions on the two outer legs of the ladder and antiferromagnetic exchange on the central leg [7].…”

“…This peak vanishes at the middle transition, which according to magnetization and specific heat data is at 5.30 K and represents antiferromagnetic order largely perpendicular to a. The most obvious candidate from the low-temperature state would be the outer (Cu2) legs of the ladder-the spins on these legs lie perpendicular to a at low temperature, with opposite legs antialigned [7]. We may thus expect to find commensurate ordering of the Cu2 sites below 5.30 K.…”

“…The magnetic order in the lowest-temperature phase has already been reported [7] [see also Fig. 1(b)], so we concentrate here on the higher-temperature phases.…”

“…Their NMR results could only be explained if the system had at least four distinct magnetic sites, at odds with the idle-spin picture. Finally, the low-temperature magnetic state was determined by neutron powder diffraction and DFT calculations to comprise mutually antialigned ferromagnetic outer legs and an antiferromagnetic inner leg, with significant canting [7], as depicted in Fig. 1(b).…”