Experimental evidence for competition of antiferromagnetic and ferromagnetic correlations in HgCr2S4

Abstract

A detailed study of poly- and single crystalline samples of the normal spinel HgCr2S4 is reported. The structural refinement reveals enhanced values of the atomic displacements suggesting closeness to a structural instability. Magnetization, electron-spin resonance and specific-heat studies document strong ferromagnetic fluctuations close to 50 K and the occurrence of complex antiferromagnetic order at TN = 22 K. We found highly unconventional behavior resembling properties of a non-collinear antiferromagnet and soft ferromagnet dependent on temperature and magnetic field. Even weak external magnetic fields disturb the antiferromagnetic order and strongly enhance the ferromagnetic correlations. The conductivity shows an insulating character with non-monotonous temperature behavior and a metal-to-insulator like transition at 80 K well above the magnetic transition. The observed anomalies are related to bond frustration due to competing magnetic exchange interactions between the Cr ions.

arXiv comment24 pages, 8 figures

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• Colossal magnetocapacitive effect in differently synthesized and doped CdCr2S4
• Optical properties of ZnCr2Se4 - Spin-phonon coupling and electronic d-d-like excitations
• Magnetic competition induced colossal magnetoresistance in n-type HgCr2Se4 under high pressures
• Line-Graph Approach to Spiral Spin Liquids
• On the complexity of spinels: Magnetic, electronic, and polar ground states
• One-third magnetization plateau in a spin-1 kagome magnet BaNi${}_3$(AsO${}_4$)${}_2$(OH)${}_2$