1. Magnetic transport properties in epitaxial Fe3O4 thin film
Chunrui Hu Yizheng Wu
Surface Physics Laboratory ,Department of Physics, Fudan University
Introduction：
Field dependence of MR% at different temperatures
Fe3O4 is one of the important 3d transition-metal oxides, high Curie temperature (858 K), presence of a metal-insulator transition MIT at around 120 K (Verwey transition),and spin polarization rate reaching 100% in theory. Therefore, Fe3O4 is expected to exhibit suitable properties for its implementation in spintronic devices.
Magnetoresistance reach maximum round at 110k, nearly 11%.
Experiment：
XRD
MgO(002)
Fe3O4(004)
MBE
RT Hall effect
RT Phall effect
Fe3O4
MgO(001)
RHEED
The 004 reflection from the Fe3O4 film is shown. Laue Oscillations indicate a very high crystalline coherence ,which also can be gained from RHEED pattern.
Phall resistivity：
ρxy=(ρ||-ρ┴)sinθcosθ fit θ，
torque: H*sin(α-θ),
α: H۷I, θ : M۷I.
No pinnacle is observed in easy axis; pinnacle in hard axis may be produced by Phall effect .
Resistivity as a function of temperature
A substantial increase of the resistivity at the Verwey transition
occurs at TV ~112 K.
Hsin(α- θ) = (1/2)Hk1sin2θ - (1/4)Hk2sin 4θ Fitting: <100> Hk1= Oe，Hk2= Oe;
<110> Hk1= Oe, Hk2= Oe.
Hall resistivity as a function of resistivity
Curve fit：σxy~σxx1.66， the origin
of this scaling is an open issue at present.
conclusion：
（1）The epitaxial films of high crystal quality are gained by Molecular Beam Epitaxy.
（2） Magnetoresistance reach maximum round at 110k.
（3） Pinnacle in hard axis may be produced by Phall effect.