Nonequilibrium Magnetic Oscillation with Cylindrical Vector Beams

Hiroyuki Fujita,Masahiro Sato

doi:10.1038/s41598-018-33651-0

Hiroyuki Fujita, Masahiro Sato

Open Access

https://doi.org/10.1038/s41598-018-33651-0

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Journal: Scientific Reports	Publication Date: Oct 24, 2018
Citations: 11	License type: open-access

Affiliation: The University of Tokyo, Ibaraki University

Abstract

Magnetic oscillation is a generic property of electronic conductors under magnetic fields and widely appreciated as a useful probe of their electronic band structure, i.e. the Fermi surface geometry. However, the usage of the strong static magnetic field makes the measurement insensitive to the magnetic order of the target material. That is, the magnetic order is anyhow turned into a forced ferrromagnetic one. Here we theoretically propose an experimental method of measuring the magnetic oscillation in a magnetic-order-resolved way by using the azimuthal cylindrical vector (CV) beam, an example of topological lightwaves. The azimuthal CV beam is unique in that, when focused tightly, it develops a pure longitudinal magnetic field. We argue that this characteristic focusing property and the discrepancy in the relaxation timescale between conduction electrons and localized magnetic moments allow us to develop the nonequilibrium analogue of the magnetic oscillation measurement. Our optical method would be also applicable to metals under the ultra-high pressure of diamond anvil cells.

Highlights

Magnetic oscillation is a generic property of electronic conductors under magnetic fields and widely appreciated as a useful probe of their electronic band structure, i.e. the Fermi surface geometry
When an electric conductor is under a strong magnetic field, the electronic band structure is reconstructed to be Landau levels, and the isoenergy surface of electrons in the momentum space reduces into the so-called Landau tubes
We propose an extension of the magnetic oscillation measurement applicable to those field-sensitive materials

Summary

Introduction

Magnetic oscillation is a generic property of electronic conductors under magnetic fields and widely appreciated as a useful probe of their electronic band structure, i.e. the Fermi surface geometry. The azimuthal CV beam is unique in that, when focused tightly, it develops a pure longitudinal magnetic field We argue that this characteristic focusing property and the discrepancy in the relaxation timescale between conduction electrons and localized magnetic moments allow us to develop the nonequilibrium analogue of the magnetic oscillation measurement. If we focus on the electronic conductivity, the oscillation is called the Shubnikov-de Haas effect, and if we on the spin polarization (or magnetic susceptibility), that is called the de Haas-van Alphen effect In the latter case, the oscillation frequency is determined by the area of the extremal orbit on the Fermi surface. If we are to apply that to conducting magnets with localized magnetic moments, a problem arises In this case, the strong static magnetic field applied to measure the oscillation itself affects the magnetic structure. We cannot obtain the full profile of the Fermi surface because the magnetic oscillation only gives the information about the Fermi surface cross section perpendicular to the applied magnetic field

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Discussion

Conclusion