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Magnetic entropy change as a probe of the phase evolution of noncollinear spin textures: An analysis of Cr1/3NbS2

When Sep 12, 2018
from 02:00 PM to 02:30 PM
Where Goldsmiths 1
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Eleanor M. Clements
Department of Physics, University of South Florida, USA

In magnetic systems that lack a center of inversion symmetry, an antisymmetric exchange term, called the Dzyaloshinskii-Moriya (DM) interaction, is allowed in the magnetic Hamiltonian. In chiral crystals, helical spin structures are stabilized by the competition between symmetric exchange and the DM interaction. As helimagnetic structures are forced to break chiral symmetry, they are protected by the underlying crystalline chirality. Thus, the application of an external magnetic field with respect to certain high symmetry directions induces metamagnetic crossovers into modulated states such as the chiral soliton lattice (CSL) and skyrmion lattice (SkL). These materials have become a center of interest for spintronics applications due to their stable, particle-like properties, and high degree of tunability via control of external parameters, such as magnetic and/or electric field and temperature. Understanding how these robust magnetic structures are stabilized is a topic of fundamental interest, especially since many structures exist only in the vicinity of T_C.

In this talk, our work is presented on the phase evolution of the CSL, first proposed by Dzyaloshinskii, which is physically realized in the monoaxial chiral helimagnet Cr1/3NbS2. An introduction on the physical background of some spatially-modulated magnetic structures will be given. I will demonstrate how we utilize the temperature and field dependence of the magnetic entropy change (DS_M), obtained from the magnetocaloric effect, as a fundamental probe of the phase transformations of complex magnetic structures. The information related to spin ordering obtained from DS_M is used to resolve details of the evolution and stabilization of the chiral magnetic phases in Cr1/3NbS2, which were not previously observed using conventional methods.

The study of functional materials has underpinned the enormous changes in information technology and electronic systems seen in the past decades. Research in the Department on device materials spans many of the most exciting areas in which the functional properties of new materials are being understood and developed.

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