Deposition and patterning of magnetic atom trap lattices in FePt films with periods down to 200nm

TL;DR

This paper demonstrates the epitaxial growth and nanoscale patterning of FePt magnetic films with periods as small as 200 nm, enabling potential applications in ultracold atom trapping for quantum simulation.

Contribution

It introduces a method combining MBE, EBL, and ion milling to create high-quality, nanoscale magnetic lattice structures in FePt films for the first time.

Findings

FePt films with high magnetic remanence and coercivity were successfully grown.

Nanoscale lattice patterns with periods down to 200 nm were fabricated.

A continuous variation of lattice constant from 5 μm to 250 nm was achieved.

Abstract

We report on the epitaxial growth and the characterization of thin FePt films and the subsequent patterning of magnetic lattice structures. These structures can be used to trap ultracold atoms for quantum simulation experiments. We use Molecular Beam Epitaxy (MBE) to deposit monocrystalline FePt films with a thickness of 50 nm. The films are characterized with X-ray scattering and Mossbauer spectroscopy to determine the long range order parameter and the hard magnetic axes. A high monocrystalline fraction was measured as well as a strong remanent magnetization of M = 900 kA/m and coercivity of 0.4 T. Using Electron Beam Lithography (EBL) and argon ion milling we create lattice patterns with a period down to 200 nm, and a resolution of 30 nm. The resulting lattices are imaged in a Scanning Electron Microscope in cross-section created by a Focused Ion Beam. A lattice with continuously varying lattice constant ranging from 5 micrometer down to 250nm has been created to show the wide range of length scales that can now be created with this technique.