Research Interests

Magnetic moment in thin ferromagnetic films

Introduction

Generally, the magnetic properties of thin films deviate from their bulk behaviour. That is also true for the magnetic moment, which depends on many parameters, e.g. the film thickness, surface/interface roughness, substrate, crystalline orientation, cap layer, temperature. It is interesting from a technological as well as theoretical point of view, e.g. to verify a definite model for the temperature dependence. The experimental task is quite challenging because in the monolayer regime the signal is quite low. SQUID magnetometry is typically not sensitive enough because of the large diamagnetic background of the substrate. We applied the technique of Torsion Oscillation Magnetometry and Polarized Neutron Reflectometry (PNR).

PNR is a powerful technique because the interaction of neutrons with the nucleus has the same order of magnitude as the interaction with the magnetization.

Results for PNR on V(110) / Fe

For this system we studied the magnetization of ultrathin uncovered Fe films epitaxially prepared on a V(110) single crystal in-situ (in UHV) with PNR. The magnetization of the thin Fe(110) layers is reduced equivalent to a magnetically dead layer (which of course does not exist!) of 0.4 nm.

References:

T. Nawrath, H. Fritzsche, F. Klose, J. Nowikow, and H. Maletta

In situ magnetometry with polarized neutrons on thin magnetic films

Phys. Rev. B 60 , 9525 (1999)

H. Fritzsche, T. Nawrath, H. Maletta, and H. Lauter

Polarized neutron reflectometry study of ultrathin Fe layers on V(110) and V(100)

Physica B 241-243 , 707 (1998)

Results for PNR on V(100) / Fe

In order to study the influence of the crystallographic orientation we also studied the system V(100)/Fe and V(100)/Fe/V.

References:

Y. T. Liu, H. Fritzsche, J. Hauschild, and H. Maletta

Polarized neutron reflectometry study of thin Fe films prepared on V(100)

Physica B 350, e225 (2004)

H. Fritzsche, Y. T. Liu, J. Hauschild, and H. Maletta

Magnetization of uncovered and V-covered ultrathin Fe(100) films on V(100)

Phys. Rev. B 70, 214406 (2004)