Abstract
The temperature-magnetic field phase diagram of the mixed honeycomb-triangular lattice system K2Mn3(VO4)2CO3 is investigated by means of magnetization, heat-capacity, and neutron-scattering measurements. The results indicate that triangular and honeycomb magnetic layers undergo sequential magnetic orderings and act as nearly independent magnetic sublattices. The honeycomb sublattice orders at about 85 K in a Neél-type antiferromagnetic structure, while the triangular sublattice displays two consecutive ordered states at much lower temperatures, 3 and 2.2 K. The ground state of the triangular sublattice consists of a planar "Y" magnetic structure that emerges from an intermediate collinear "up-up-down" state. Applied magnetic fields parallel or perpendicular to the c axis induce exotic ordered phases characterized by various spin-stacking sequences of triangular layers that yield bilayer, three-layer, or four-layer magnetic superstructures. The observed superstructures cannot be explained in the framework of quasiclassical theory based only on nearest-neighbor interlayer coupling and point towards the presence of effective second-nearest-neighbor interactions mediated by fluctuations of the magnetic moments in the honeycomb sublattice.
| Original language | English |
|---|---|
| Article number | 011038 |
| Journal | Physical Review X |
| Volume | 9 |
| Issue number | 1 |
| DOIs | |
| State | Published - Feb 26 2019 |
Funding
Work at the Oak Ridge National Laboratory is sponsored by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Scientific User Facilities Division (neutron scattering) and Materials Sciences and Engineering Division (magnetization and heat-capacity analysis). The authors also acknowledge the financial support from the National Science Foundation under Grant No. DMR-1410727. A portion of this work is performed at the National High Magnetic Field Laboratory (NHMFL), which is supported by National Science Foundation Cooperative Agreement No. DMR-1157490 and the State of Florida. We acknowledge Stan Tozer for use of his 16-T PPMS which is supported by the NHMFL and the Center for Actinide Science and Technology, an EFRC funded by the DOE-BES under Grant No. DE-SC0016568. V.\u2009O.\u2009G. thanks X. Wang for the help provided with the TOPAZ single-crystal data refinement and I. Zaliznyak for useful discussions. This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan.