New magnetic phases in thin terbium films

F H S Sales,A S Carriço,L L Oliveira,A L Dantas

doi:10.1063/1.5129877

Abstract

We report a theoretical investigation of new magnetic phases of thin terbium (Tb) films in the temperature interval between 220 K and 280 K, and under external magnetic field strengths ranging from 50 Oe to 1 kOe. We show that surface effects may produce relevant changes in the helimagnetic phase, such as the nucleation of alternating-helix phases. Changes in the exchange energy balance near the surface, favor the alignment with the external field and the nucleation of the alternating-helix phase.

Highlights

INTRODUCTIONConsiderable research effort has recently been dedicated to investigating the impact of confinement as well as surface effects on the equilibrium phases of magnetic systems with size comparable to fundamental magnetic lengths.1–10
Considerable research effort has recently been dedicated to investigating the impact of confinement as well as surface effects on the equilibrium phases of magnetic systems with size comparable to fundamental magnetic lengths.1–10These confinement and surface effects are interesting in magnetic systems in which the leading bulk magnetic phases consist of patterns made of a periodical repetition of units containing a finite number of spins
It has been theoretically shown that wide thermal hysteresis loops may be induced in Dy thin films subjected to external magnetic fields of modest strength

Summary

INTRODUCTION

Considerable research effort has recently been dedicated to investigating the impact of confinement as well as surface effects on the equilibrium phases of magnetic systems with size comparable to fundamental magnetic lengths.1–10 These confinement and surface effects are interesting in magnetic systems in which the leading bulk magnetic phases consist of patterns made of a periodical repetition of units containing a finite number of spins. In thin films the near surface region has a relevant change in the balance of first and second neighbors exchange energies These two features allows the manipulation of the helimagnetic order of thin Tb with relatively modest external field values. We present a theoretical discussion of the nucleation of alternating-helix phases in thin terbium films These phases are associated to the confinement of surface atoms magnetic moments directions to directions near the external field direction.

THEORETICAL MODEL

RESULTS

CONCLUSIONS