6 research outputs found
Perpendicularly magnetized Mn-Co-Ga-based thin films with high coercive field
MnCoGa epitaxial thin films were grown on MgO substrates by
magnetron co-sputtering. Structures were tetragonal or cubic depending on Co
content. Composition dependence of saturation magnetization and uniaxial
magnetic anisotropy of the films were investigated. A high (1.2 MJ
m) was achieved for the MnCoGa film with the
magnetic moment 0.84. Valence band spectra were obtained by hard X-ray
photoelectron spectroscopy. Sharp peaks in the cubic case, which were absent in
the tetragonal case, prove that a van Hove singularity causes a band
Jahn-Teller effect with tetragonal distortion. Observations agree well with the
first-principles calculations
Completely compensated ferrimagnetism and sublattice spin crossing in the half-metallic Heusler compound Mn1.5FeV0.5Al
The Slater-Pauling rule states that L21 Heusler compounds with 24 valence
electrons do never exhibit a total spin magnetic moment. In case of strongly
localized magnetic moments at one of the atoms (here Mn) they will exhibit a
fully compensated half-metallic ferrimagnetic state instead, in particular,
when symmetry does not allow for antiferromagnetic order. With aid of magnetic
and anomalous Hall effect measurements it is experimentally demonstrated that
Mn1.5V0.5FeAl follows such a scenario. The ferrimagnetic state is tuned by the
composition. A small residual magnetization, that arises due to a slight
mismatch of the magnetic moments in the different sublattices results in a
pronounced change of the temperature dependence of the ferrimagnet. A
compensation point is confirmed by observation of magnetic reversal and sign
change of the anomalous Hall effect. Theoretical models are presented that
correlate the electronic structure and the compensation mechanisms of the
different half-metallic ferrimagnetic states in the Mn-V-Fe-Al Heusler system.Comment: Under revie
From colossal to zero: Controlling the Anomalous Hall Effect in Magnetic Heusler Compounds via Berry Curvature Design
Since the discovery of the anomalous Hall effect (AHE), the anomalous Hall
conductivity (AHC) has been thought to be zero when there is no net
magnetization. However, the recently found relation between the intrinsic AHE
and the Berry curvature predicts other possibilities, such as a large AHC in
non-colinear antiferromagnets with no net magnetization but net Berry
curvature. Vice versa, the AHE in principle could be tuned to zero,
irrespective of a finite magnetization. Here, we experimentally investigate
this possibility and demonstrate that, the symmetry elements of Heusler magnets
can be changed such that the Berry curvature and all the associated properties
are switched while leaving the magnetization unaffected. This enables us to
tune the AHC from 0 {\Omega}-1cm-1 up to 1600 {\Omega}-1cm-1 with an
exceptionally high anomalous Hall angle up to 12 %, while keeping the
magnetization same. Our study shows that the AHC can be controlled by
selectively changing the Berry curvature distribution, independent of the
magnetization.Comment: Published in Physical Review X. 16 pages, 5 figure