Magnetocrystalline anisotropy and dynamic spin reorientation of half-doped Nd_(0.5)Pr_(0.5)FeO_(3)single crystal

The single crystals of Nd_(0.5)Pr_(0.5)FeO_(3)were successfully grown by optical floating zone method.Room temperature x-ray diffraction and Laue photograph declared the homogeneity and high quality of the crystal.The significant magnetic anisotropy and multiple magnetic transitions illustrate the complex magnetic structure.At high temperatures(T>66 K),it shows the typical characteristics ofΓ_(4)(G_(x),A_(y),F_(z))state.With the decrease of the temperature,it undergoes a first-order spin reorientation transition fromΓ_(4)(G_(x),A_(y),F_(z))toΓ_(2)(F_(x),C_(y),G_(z))state in the temperature window of 45-66 K under an applied magnetic field of 0.01 T.As the temperature drops to~17 K,a new magnetic interaction mechanism works,which results in a further enhancement of magnetization.The T-H phase diagram of Nd_(0.5)Pr_(0.5)FeO_(3)single crystal was finally constructed.

Negative dependence of surface magnetocrystalline anisotropy energy on film thickness in Co_(33)Fe_(67) alloy

In this work, the magnetocrystalline anisotropy energy(MAE) on the surface of FeCoalloy film is extracted from x-ray magnetic linear dichroism(XMLD) experiments. The result indicates that the surface MAE value is negatively correlated with thickness. Through spectrum calculations and analysis, we find that besides the thickness effect, another principal possible cause may be the shape anisotropy resulting from the presence of interface roughness. These two factors lead to different electron structures on the fermi surface with different exchange fields, which produces different spin–orbit interaction anisotropies.

First principles study on the magnetocrystalline anisotropy of Fe-Ga magnetostrictive alloys

This paper investigates the electronic structure and magnetocrystalline anisotropy of Fe--Ga magnetostrictive material by means of the full potential-linearized augmented plane-wave method within the generalized gradient approximation. The 3d-orbit splitting of Fe atoms in D03, B2-like and L12 crystalline structures of Fe-Ga is calculated with consideration of the crystal field as well as the spin-orbit coupling effect. Because of the frozen orbital angular momenta of the 3d-orbit for Fe atoms in Fe-Ga magnetostrictive alloys and the spin-orbit coupling, the distribution of the electron cloud is not isotropic, which leads to the anisotropy of exchange interaction between the different atoms. A method on estimating the magnetocrystalline anisotropy of Fe-Ga alloys by means of calculating orbit-projected density of states for Fe atoms is performed. The anisotropic distribution of the electron cloud of Fe atoms in these three crystalline structures of Fe-Ga is studied based on the above method showing the highest magnetic anisotropy for B2-like structure. This qualitative method comes closer to physical reality with a vivid physical view, which can evaluate the anisotropy of electron cloud for 3d transition atoms directly. The calculated results are in good agreement with both the previous theoretical computation and the tested value on the magnetic anisotropy constant, which confirms that the electron cloud anisotropy of Fe atoms could well characterize the magnetocrystalline anisotropy of Fe-Ga magnetostrictive material.

Fabrication and magnetocrystalline anisotropy of NiCo(002) films

A series of 30-nm-thick epitaxial NixCo1-x （002） alloy films are fabricated by DC magnetron sputtering. MgO （002） and SrTiO3 （002） single substrates are used for x 〉 0.5 and x 〈 0.5, respectively. The magnetocrystalline anisotropy of NixCO1-x （002） alloy films is studied in the entire composition region for 0 ≤ x ≤ 1.0. When x decreases, the cubic magnetic anisotropy constant K1 changes sign from negative to positive atx = 0.96 and becomes negative again atx = 0.79. It becomes more negative as x decreases from 0.79 to 0. The uniaxial anisotropy Ku is smaller than the K1 by a factor of two orders.

Ultrathin nanosheets of Mn3O4： A new two-dimensional ferromagnetic material with strong magnetocrystalline anisotropy

Two-dimensional （2D） materials with robust ferromagnetism have played a key role in realizing next- generation spin-electronic devices, but many challenges remain, especially the lack of intrinsic ferro- magnetic behavior in almost all 2D materials. Here, we highlight ultrathin Mn3O4 nanosheets as a new 2D ferromagnetic material with strong magnetocrystalline anisotropy. Magnetic measurements along the in-plane and out-of-plane directions confirm that the out-of-plane direction is the easy axis. The 2D-confined environment and Rashba-type spin-orbit coupling are thought to be responsible for the magnetocrystaUine anisotropy. The robust ferromagnetism in 2D MnaO4 nanosheets with magne- tocrystalline anisotropy not only paves a new way for realizing the intrinsic ferromagnetic behavior in 2D materials but also provides a novel candidate for building next-generation spin-electronic devices.

Achieving Ultra-Broad Microwave Absorption Bandwidth Around Millimeter-Wave Atmospheric Window Through an Intentional Manipulation on Multi-Magnetic Resonance Behavior

The utilization of electromagnetic waves is rapidly advancing into the millimeter-wave frequency range,posing increasingly severe challenges in terms of electromagnetic pollution prevention and radar stealth.However,existing millimeter-wave absorbers are still inadequate in addressing these issues due to their monotonous magnetic resonance pattern.In this work,rare-earth La^(3+)and non-magnetic Zr^(4+)ions are simultaneously incorporated into M-type barium ferrite(BaM)to intentionally manipulate the multi-magnetic resonance behavior.By leveraging the contrary impact of La^(3+)and Zr^(4+)ions on magnetocrystalline anisotropy field,the restrictive relationship between intensity and frequency of the multi-magnetic resonance is successfully eliminated.The magnetic resonance peak-differentiating and imitating results confirm that significant multi-magnetic resonance phenomenon emerges around 35 GHz due to the reinforced exchange coupling effect between Fe^(3+)and Fe^(2+)ions.Additionally,Mosbauer spectra analysis,first-principle calculations,and least square fitting collectively identify that additional La^(3+)doping leads to a profound rearrangement of Zr^(4+)occupation and thus makes the portion of polarization/conduction loss increase gradually.As a consequence,the La^(3+)-Zr^(4+)co-doped BaM achieves an ultra-broad bandwidth of 12.5+GHz covering from 27.5 to 40+GHz,which holds remarkable potential for millimeter-wave absorbers around the atmospheric window of 35 GHz.

Magnetocrystalline Anisotropies of RFe_(10)V_2 (R=Y, Tb, Dy, Ho, and Er) and Their Hydrides

The magnetocrystalline anisotropies of RFe10V2 (R=Y, Tb, Dy, Ho and Er) and their hydrides were studied by X-ray diffraction, magnetization and a.c. susceptibility measurements. The uniaxial anisotropy of Fe-sublattice and R-sublattice with positive second order Stevens αJ in RFe10V2 compounds is weakened by hydrogenation, while that of R-sublattice with negative αJ (Er) enhanced. Such a change of anisotropy causes planar-easy magnetic structures in RFe10V2 (R=Tb and Dy) at room temperature and induces spin reorientation in HoFe10V2 after hydrogenation. The change of anisotropy of R-sublattice after hydrogenation may be owed to a decrease of the second order crystalline coefficient.

Low field induced giant anisotropic magnetocaloric effect in DyFeO_3 single crystal

We have investigated the anisotropic magnetocaloric effect and the rotating field magnetic entropy in Dy FeO3 single crystal. A giant rotating field entropy change of -ΔSM^R = 16.62 J/kg·K was achieved from b axis to c axis in bc plane at 5 K for a low field change of 20 k Oe. The large anisotropic magnetic entropy change is mainly accounted for the 4 f electron of rare-earth Dy^3＋ ion. The large value of rotating field entropy change, together with large refrigeration capacity and negligible hysteresis, suggests that the multiferroic ferrite Dy FeO3 singlecrystal could be a potential material for anisotropic magnetic refrigeration at low field, which can be realized in the practical application around liquid helium temperature region.

Structural and Magnetic Properties of the New Type of Rare Earth-Iron-Nitrogen Intermetallic Compounds

We succeed in inserting a number of nitrogen atoms into the R_2Fe_(17)and RTiFe_(11)intermetallic compounds.The nitrides retain original Th_2Zn_(17)(or Th_2Ni_(17_)and ThMn_(12)structures,but with an increase in the unit cell volume.The interstitial nitrogen atoms are found to have an effect of increasing the Curie tempera- ture and saturation magnetization.Moreover,a distinct effect on the magnetocrystalline anisotropy is also ob- served in these nitride compounds.Especially,NdTiFe_(11)N_(0.5)and SmTiFe_(11)N_2 have excellent intrinsic magnetic properties favourable for permanent magnet applications.

Structure, morphology, and magnetic properties of high-performance NiCuZn ferrite

High-performance submicron-scaled NiCuZn ferrites are prepared by the solid-state reaction method through using CuO as additive. In the synthesis process, a mixture of superfine powder is sintered at 900？C for 3 h, and the obtained product is Ni Zn-ferrite with spinel structure. We observe that the particle size increases with raising the sintering temperature. The NiCuZn ferrite with relatively uniform size and granular shape has the best performance： its coercivity is 14 Oe（1 Oe = 79.5775 A·m^-1） and saturation magnetization is 48 emu/g. We also study the effects of particle size, magnetocrystalline anisotropy, and microstructure on coercivity. The method presented here is convenient and economical for producing the high-permeability ferrite powders.

Modeling of Orientation and Alignment of Primary Al_3Ni Crystal in Al-Ni Alloy by Imposing a High Magnetic Field

Regarding Al_3Ni crystal as a rigid ellipsoid,a model describing the orientation and alignment of a primary paramagnetic Al_3Ni crystal in Al- Ni alloy solidification under a high magnetic field is developed.The model is based on rigid body rotation dynamics model as well as the magnetic dipole model,respectively.It describes the rotational motion of a magnetic anisotropic crystal around its centroid and around one endpoint of its crystal axis.The orientation time and the orientation characteristics with the intensity of magnetic field,the aspect ratio of the crystal and the effective viscosity of the melt,as well as the crystal growth,are deeply discussed for single grain.Furthermore,the interaction between two crystals during the alignment in high magnetic field are analyzed based on the magnetic dipole model,in which the final state of the grain is dependent on the attractive interaction force between two neighboring grains and the magnetization force acting on each grain.The prediction shows fitness with the experimental and theoretical results in literature.

Large magnetocaloric effect and magnetoresistance in ErNi single crystal

The magnetic properties,magnetocaloric effect and magnetoresistance in Er Ni single crystal have been investigated in detail.With decreasing temperature,Er Ni single crystal undergoes two successive magnetic transitions:a paramagnetic to ferromagnetic transition at T_(C)=11 K and a spin-reorientation transition at TS_(R)=5 K.Meanwhile,a sharp field-induced metamagnetic transition is observed below the T_(C)along the a axis.Er Ni single crystal possesses a giant magnetocaloric effect around T_(C).The maximum magnetic entropy change is-36.1 J(kg K)^(-1)along the a axis under the field change of 0-50 k Oe.In particular,the rotating magnetocaloric effect in Er Ni single crystal reaches its maximum under a relatively low field,and the maximum rotating entropy change with a value of 9.3 J(kg K)^(-1)is obtained by rotating the applied field from the[011]to[100]directions under 13 k Oe.These results suggest that Er Ni could be a promising candidate for magnetic refrigeration working at liquid-helium temperature region.Moreover,a complicated transport behavior is uncovered in Er Ni single crystal,which is attributed to the complex magnetic states and magnetic polaronic effect.Both positive and negative magnetoresistance are observed.A considerable large magnetoresistance with the value of-34.5%is acquired at 8 K under50 k Oe when the field is along the[100]direction.