We describe a proof-of-principle experiment on a fully permanent magnet atom chip. We study ultracold atoms and produce a Bose-Einstein condensate (BEC). The magnetic trap is loaded efficiently by adiabatic transport of a magnetic trap via the application of uniform external fields. Radio frequency spectroscopy is used for in-trap analysis and to determine the temperature of the atomic cloud. The formation of a Bose-Einstein condensate is observed in time-of-flight images and as a narrow peak appearing in the radio frequency spectrum.
Abstract. We present designs for Ioffe-Pritchard type magnetic traps using planar patterns of hard magnetic material. Two samples with different pattern designs were produced by spark erosion of 40 µm thick
In this work FePt hard magnetic films were prepared with a thickness of 250 and 500 nm for making atom chips. We choose FePt because it has high magnetocrystalline anisotropy as well as high saturation magnetization. The FePt films were deposited at room temperature and at 350°C using Molecular Beam Epitaxy on a Si substrate. After post annealing, the samples have high in-plane and out-of-plane coercivity (H c = 8.0 kOe and 8.34 kOe, respectively) and remanent magnetization (M r /M s = 0.90, 0.93, respectively). Whereas the samples deposited at room temperature have many cracks on the surface, the samples deposited at 350 °C are free of cracks and their surfaces are mirror-like. The magnetized sample keeps the magnetization after baking in vacuum at 170 °C for 24 hours. A calculation shows that such samples can be used to trap cold atoms after lithographic patterning. IntroductionAtom chips are planar microstructures that generate magnetic fields in which lasercooled atoms can be trapped. Nowadays most of the atom chip designs are using current carrying wires to produce the minimum of the magnetic field [1,2]. If the laser-cooled atoms are in low-field-seeking states, they can be trapped by the minimum of the magnetic field. Hard magnetic films have great potential [3,4] as atom chips and have several advantages over current-carrying wires: more stable magnetic stray field, larger field gradient, no ohmic heating, and absence of current noise. Also some interesting patterns are topologically impossible with current-carrying wires.This application of hard magnetic film poses specific requirements: the thickness of the magnetic layer should be at least 200 nm in order to produce enough stray field; the magnetic moments should be completely in-plane or out-of plane and have high coercivity; the surface should be mirror-like to reflect lasers for cooling down the atoms. Finally the film should also be homogeneous, stable and bakeable.FePt has been studied extensively both in bulk [5,6] and thin film [7][8][9][10][11] form since it combines high magneto-crystalline anisotropy with high M s [12] and corrosion resistance. The FePt phase diagram shows a disordered face-centered cubic (fcc) structure at high temperature, which is magnetically soft. At lower temperatures, the Fe and Pt order in an atomic multilayer structure. This face-centered tetragonal (fct or L1 0 ) phase has very high magneto-crystalline anisotropy and coercivity.It has been shown [13] that annealing of the soft fcc material produces nanocrystallites of the fct phase that are exchange coupled to the soft phase, resulting in a material with the optimum properties desired here.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.