Host:
Oded Milo


Speaker:
Yonathan Anahory

Title:


Scanning SQUID-on-tip microscopy of non-trivial ferromagnetic materials
Yonathan Anahory

Abstract

The SQUID-on-tip lab is finally operational, after 4 years planning and building. In this seminar I will present two of the themes that we are currently exploring. The first topic is related to magnetism and in particular exchange bias. The phenomenon is usually studied in the context of magnetic interfaces between antiferromagnets and ferromagnets, where the exchange field of the former acts as a means to pin the magnetization of the latter. I will report an unusual instance of this phenomenon in the topological Weyl semimetal Co3Sn2S2, where the magnetic interfaces associated with domain walls suffice to bias the entire ferromagnetic bulk. Remarkably, our data suggests the presence of a hidden order parameter whose behavior can be independently tuned by applied magnetic fields.
The second topic is related to ferromagnetic superconducting heterostructures. The consequences of coupling between ferromagnetic insulators (FI) and superconductors (SC) are a topic of wide investigation. In particular, the proximity effect at the FI-SC interface combined with large Spin-Orbit Coupling (SOC) of the charge carriers was shown to strongly influence transport properties of the material. This is manifested in a dependance between the SC critical current and the magnetic state of the magnet. I will show scanning Squid-On-Tip (SOT) microscopy in order to image the magnetic response driven by a charge current. Furthermore, magnetic images that spatially resolve wave-like features characterized by a length scale on the order of 1 m. These preliminary results suggest the existence of unconventional current distribution and/or in-homogeneous spin accumulation.

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