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Title: Spin-glass behavior and vacancy order in van der Waals layered β - MoCl 4

Two-dimensional $${\beta}\text{-}{\mathrm{MoCl}}_{4}$$ is an attractive material from the perspectives of magnetism in $4d$ transition metal compounds, geometrically frustrated lattices, and magnetic van der Waals layered materials, but the magnetism in this compound has not been particularly well studied to date. In this paper the magnetic properties and crystal structure of $${\mathrm{MoCl}}_{4}$$ are revisited, and results of ac and dc magnetic measurements and single crystal x-ray diffraction are reported. Crystals grow as well-formed and easily cleaved hexagonal plates that are unstable in air. The revised structural model comprises $${\mathrm{CdCl}}_{2}$$-type layers with 50% Mo vacancies distributed over the sites of the triangular cation net. Interestingly, a structural ambiguity regarding the vacancy distribution is identified in the analysis of the diffraction data. The orbital moment is not expected to be quenched in this $$4{d}^{2}$$ compound. Accordingly, magnetization measurements indicate an effective moment that is about 20% lower than the spin-only value. The magnetic data reveal an anomaly near 5 K, below which a divergence of field-cooled and zero-field-cooled dc magnetization, a slow relaxation of thermoremanent magnetization, and enhanced frequency dependence of ac magnetization are observed. Finally and thus, $${\beta}\text{-}{\mathrm{MoCl}}_{4}$$ represents an uncommon example of a cleavable spin-glass system.
Authors:
 [1] ;  [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division
Publication Date:
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Physical Review Materials
Additional Journal Information:
Journal Volume: 2; Journal Issue: 7; Journal ID: ISSN 2475-9953
Publisher:
American Physical Society (APS)
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; crystal structure; magnetism; spin glasses; AC susceptibility measurements; crystallography; DC susceptibility measurements
OSTI Identifier:
1462846
Alternate Identifier(s):
OSTI ID: 1462140