Heat capacity signature of frustrated trimerons in magnetite

Abstract

Recently it has been proposed that the long-range electronic order formed by trimerons in magnetite should be frustrated due to the great degeneracy of arrangements linking trimerons. This result has important consequences as charge ordering from the condensed minority band electrons leads to a complex 3D antiferro orbital order pattern. Further more, the corner sharing tetrahedra structure of spinel B-sites supports frustration for antiferromagnetic alignments. Therefore frustration due to competing interactions will itself induce disorder and very likely frustration in the spin orientations. Here we present very low temperature specific heat data that show two deviations to the magnons and phonons contributions, that we analyze in terms of Schottky-type anomalies. The first one is associated with the thermal activation across both ferroelastic twin and ferromagnetic anti-phase domains. The second Schottky-type anomaly displays an inverse (1/H) field dependence which is a direct indication of the disordered glassy network with macroscopically degenerated singular ground states.

Two-Dimensional Cobalt(II) Benzoquinone Frameworks for Putative Kitaev Quantum Spin Liquid Candidates

“…However, an upturn in C p (T) is observed at low temperatures (below 0.1 K) and low fields (below 3 T). This upturn tail might be a manifestation of a frustrated magnetic lattice . No sharp λ-like anomaly is observed down to 0.055 K from the C p (T) data, indicating the absence of long-range magnetic ordering.…”

Magnetic field induced structural changes in magnetite observed by resonant x-ray diffraction and Mössbauer spectroscopy

“…3(a). 2 First, the sample was FC down to 8 K in the magnetic field of 2 T, high enough to uniquely define the basic c M axis along the [010] direction [51] [left panel in Fig. 3(a)].…”

“…Deep insight into excited states presents another challenge. Nevertheless, the anomalies at the low-T specific heat [2], the anomalies in AC magnetic susceptibility at approximately 20 and 60 K [3,4], and its multiferroic properties [5] suggest that several interactions and several subsystems, such as the lattice, the charge, and its distribution (orbital order), as well as magnetic subsystem, exist and exhibit themselves in the low-temperature monoclinic Cc phase below T V .…”