Angle-resolved magnetometry for determination of magnetic anisotropy in low symmetry environments: a few additions to the presentation of Dr. ShangDa Jiang Roberta Sessoli . Department of Chemistry and INSTM research unit, University of Florence ECMM 2013 – Satellite workshop – October 11-12, 2013 1
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Angle-resolved magnetometry for determination of
magnetic anisotropy in low symmetry environments:
a few additions to the presentation of
Dr. ShangDa Jiang
Roberta Sessoli.
Department of Chemistry and INSTM research unit, University of Florence
ECMM 2013 – Satellite workshop – October 11-12, 2013
1
Techniques for the determination of the magnetic anisotropy
STM
Anisotropy parameters Anisotropy axes orientation
•(HF-)EPR on powder
• Inelastic Neutron Scattering
•Magnetometry on powder
•Specific heat on powder
•(HF-)EPR on single crystal
•Torque Magnetometry
•Angle resolved magnetometry
2
Angular resolved magnetometry: the rotator
STMAn old technique
revisited thanks to the
automation & precision of
horizontal sample rotator
combined high sensitivity
of modern SQUID
magnetometers
H
Internal rod
External rod
Sample
holder
Wire &
spring
3
H
Angular resolved magnetometry: the crystal
STM
0 -1 -1
0 -1 1
-1 0 1
• 1st step: Accurate indexing of the faces
2nd step: Three rotations along orthogonal
axes allow a full characterization of the
magnetic anisotropy without a priori
information
H
1°rot 2°rot 3°rot
?
4
Angular resolved magnetometry: the support
STM
H H
1°rot 2°rot 3°rot
?
A teflon cube
x
y
z
5
STM
SMM
The laboratory reference frame
By indexing with a single crystal X-ray diffractometer the
faces of the amorphous cube on which the crystal is
glued, the laboratory reference frame is defined in the