Spin-Flop Transition in Atomically Thin MnPS3 Crystals - Interfaces beyond the elastic approximation

01.10.2019 13:00 – 15:00

We investigate vertical transport through tunnel barriers of MnPS3, a van der
Waals semiconductor whose individual layers are easy-axis antiferromagnets.
We nd a sizable temperature dependent magnetoresistance that sets-in below
approximately T  78 K {the bulk Neel temperature TN{ due to a spin-
op
transition occurring at 0H  5 T { the same value at which the spin-
op
transition is observed in bulk MnPS3 (Fig.1a). The phenomenon persists down
to individual monolayers, with nearly unchanged critical temperature and
spin-
op eld (Figs. 1b, c), albeit with a dierent dependence on H eld. We
discuss the implications of these ndings for the magnetic state of atomically
thin MnPS3 crystals, conclude that antiferromagnetic correlations persist down
to the level of individual monolayers, and that tunneling magnetoresistance
does allow magnetism in 2D insulating materials to be detected even in the
absence of spin-ltering.


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Diverse systems including ferroic domain walls, cell fronts, or contact lines
have been usually described as disordered elastic systems, even when critical
hypotheses of the theory are not satised. Solving domain walls dynamics and
statics beyond the elastic approximation is still a largely open
theoretical/analytical problem. In this work, we propose to address it by
analyzing a Ginzburg-Landau model, which describes the main dynamics of
driven systems and where interfaces with bubbles and overhangs can be
studied. We show the connection between the two-dimensional
Ginzburg-Landau model and the one-dimensional elastic description for
disordered systems and probe the validity of the elastic theory as a function of
defects. We examine observables such as the interface roughness and the
structure factor, both numerically and analytically. Our simulations and
calculations, in addition to making contact with experiments, allow to test and
provide insight to develop new analytical approaches to this problem.

Lieu

Bâtiment: Ecole de Physique

Auditoire Stückelberg

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