اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدUnraveling the influence of electronic and magnonic spin current injection near the magnetic ordering transition of IrMn metallic antiferromagnets
49
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
Although spin injection at room temperature in an IrMn metallic antiferromagnet strongly depends on the transport regime, and is more efficient in the case of magnonic transport, in this article, we present experimental data demonstrating that the enhanced efficiency of spin injection caused by spin fluctuations near the ordering temperature can be as efficient for the electronic and magnonic transport regimes. By selecting representative interacting environments, we also demonstrated that the amplification of spin injection near the ordering temperature of the IrMn antiferromagnet is independent of exchange coupling with an adjacent NiFe ferromagnet. In addition, our findings confirm that the spin current carried by magnons penetrates deeper than that transported by conduction electrons in IrMn. Finally, our data indicates that the value of the ordering temperature for the IrMn antiferromagnet is not significantly affected by either the electronic or magnonic nature of the spin current probe, or by exchange coupling.
قيم البحث
اقرأ أيضاً
Theoretical predictions of the magnetic anisotropy of antiferromagnetic materials are demanding due to a lack of experimental techniques which are capable of a direct measurement of this quantity. At the same time it is highly significant due to the
use of antiferromagnetic components in magneto-resistive sensor devices where the stability of the antiferromagnet is of upmost relevance. We perform an ab-initio study of the ordered phases of IrMn and IrMn3, the most widely used industrial antiferromagnets. Calculating the form and the strength of the magnetic anisotropy allows the construction of an effective spin model, which is tested against experimental measurements regarding the magnetic ground state and the Neel temperature. Our most important result is the extremely strong second order anisotropy for IrMn3 appearing in its frustrated triangular magnetic ground state, a surprising fact since the ordered L12 phase has a cubic symmetry. We explain this large anisotropy by the fact that cubic symmetry is locally broken for each of the three Mn sub-lattices.
High entropy oxides (HEOs) are a rapidly emerging class of chemically complex functional materials. The original paradigm of HEOs assumes cationic occupations with the highest possible configurational entropy allowed by the composition and crystallog
raphic structure. However, the fundamental question remains on the actual degree of configurational disorder and its subsequent stabilizing role in HEOs. Considering the experimental limitations due to the inherent chemical complexity of HEOs, here we utilize a robust and cross-referenced characterization approach using soft X-ray magnetic circular dichroism, hard X-ray absorption spectroscopy, Mossbauer spectroscopy, neutron powder diffraction and SQUID magnetometry to study the competition between enthalpy and configurational entropy on a lattice level in a model spinel HEO (S-HEO), (Co$_{0.2}$Cr$_{0.2}$Fe$_{0.2}$Mn$_{0.2}$Ni$_{0.2}$)$_3$O$_4$. In contrast to the previous studies, the derived complete structural and spin-electronic model, (Co$_{0.6}$Fe$_{0.4}$)(Cr$_{0.3}$Fe$_{0.1}$Mn$_{0.3}$Ni$_{0.3}$)$_2$O$_4$, highlights a significant deviation from the hitherto assumed paradigm of entropy-driven non-preferential distribution of cations in HEOs. An immediate correlation of this result can be drawn with bulk as well as the local element specific magnetic properties, which are intrinsically dictated by cationic occupations in spinels. The real local lattice picture presented here provides an alternate viewpoint on ionic arrangement in HEOs, which is of fundamental interest for predicting and designing their structure-dependent functionalities.
Magnetic junction is considered which consists of two ferromagnetic metal layers, a thin nonmagnetic spacer in between, and nonmagnetic lead. Theory is developed of a magnetization reversal due to spin injection in the junction. Spin-polarized curren
t is perpendicular to the interfaces. One of the ferromagnetic layers has pinned spins and the other has free spins. The current breaks spin equilibrium in the free spin layer due to spin injection or extraction. The nonequilibrium spins interact with the lattice magnetic moment via the effective s-d exchange field, which is current dependent. Above a certain current density threshold, the interaction leads to a magnetization reversal. Two threshold currents are found, which are reached as the current increases or decreases, respectively, so that a current hysteresis takes place. The theoretical results are in accordance with the experiments on magnetization reversal by current in three-layer junctions Co/Cu/Co prepared in a pillar form.
Spin nutation resonance has been well-explored in one-sublattice ferromagnets. Here, we investigate the spin nutation in two-sublattice antiferromagnets as well as, for comparison, ferrimagnets with inter-and intra-sublattice nutation coupling. In pa
rticular, we derive the susceptibility of the two-sublattice magnetic system in response to an applied external magnetic field. To this end, the antiferromagnetic and ferrimagnetic (sub-THz) precession and THz nutation resonance frequencies are calculated. Our results show that the precession resonance frequencies and effective damping decrease with intra-sublattice nutation coupling, while they increase with inter -sublattice nutation in an antiferromagnet. However, we find that the THz nutation resonance frequencies decrease with both the intra-and inter-sublattice nutation couplings. For ferrimagnets, conversely, we calculate two nutation modes with distinct frequencies, unlike antiferromagnets. The exchange-like precession resonance frequency of ferrimagnets decreases with intra-sublattice nutation coupling and increases with inter-sublattice nutation coupling, like antiferromagnets, but the ferromagnetic-like precession frequency of ferrimagnets is practically invariant to the intra and inter-sublattice nutation couplings.
We report on the influence of the improved L21 ordering degree on the magnetic properties of Co2MnSi Heusler films. Different fractions of the L21 phase are obtained by different post-growth annealing temperatures ranging from 350 degC to 500 degC. R
oom temperature magneto-optical Kerr effect measurements reveal an increase of the coercivity at an intermediate annealing temperature of 425 degC, which is a fingerprint of an increased number of pinning centers at this temperature. Furthermore, Brillouin light scattering studies show that the improvement of the L21 order in the Co2MnSi films is correlated with a decrease of the saturation magnetization by about 9%. The exchange stiffness constant of Co2MnSi, however, increases by about 8% when the L21 order is improved. Moreover, we observe a drop of the cubic anisotropy constant K1 by a factor of 10 for an increasing amount of the L21 phase.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
