Title: Spin-glass behavior and vacancy order in van der Waals layered $\beta \text{-}{\mathrm{MoCl}}_4$

Abstract

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:

McGuire, Michael A. ^[1]; Sales, Brian C. ^[1]

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+ Show Author Affiliations

1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division

Publication Date:

2018-07-30

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)

OSTI Identifier:

1462846

Alternate Identifier(s):

OSTI ID: 1462140

Grant/Contract Number:  

AC05-00OR22725

Resource 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)

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; crystal structure; magnetism; spin glasses; AC susceptibility measurements; crystallography; DC susceptibility measurements