A Giant Exchange Bias Effect Due to Enhanced Ferromagnetism Using a Mixed Martensitic Phase in NiMnGa Spun Ribbons.

The structure of a material is an important factor in determining its physical properties. Here, we adjust the structure of the NiMnGa spun ribbons by changing the wheel speed to regulate the exchange bias effect of the material. The characterization results of micromorphology and structure show that as the wheel speed increases, the martensite lath decreases from 200 nm to 50 nm, the structure changed from the NM to a NM and 10M mixed martensitic structure containing mainly NM, then changed to NM and 10M where 10M and NM are approaching.

Magnetic and Magnetostrictive Behaviors of Laves-Phase Rare-Earth-Transition-Metal Compounds TbDyCo.

The magnetic morphotropic phase boundary (MPB) was first discovered in Laves-phase magnetoelastic system Tb-Dy-Co alloys (PRL 104, 197201 (2010)). However, the composition-dependent and temperature-dependent magnetostrictive behavior for this system, which is crucial to both practical application and the understanding of transitions across the MPB, is still lacking. In this work, the composition-dependence and temperature-dependence of magnetostriction for TbDyCo (x = 0.

A three-dimensional crosslinked nano-structure growth of carbon nanotube/cobalt sulfide composites on porous carbon nanofibers for enhanced sodium storage.

A three-dimensional crosslinked CFs@CNT/CoS nanocomposite was successfully synthesized by growing carbon nanotubes on carbon nanofibers and a facile sulfurization process. The carbon nanotubes synthesized by sintering melamine under the catalysis of cobalt can increase the specific surface areas and provide abundant sodium ion diffusion channels for the composite. Meanwhile, the formed cobalt sulfide nanoparticles will increase the active sites on the surface of CFs@CNT/CoS.

Giant exchange bias induced tuning interfacial spins in polycrystalline FeO/CoO bilayers.

A giant exchange bias (EB) of 9600 Oe was observed in polycrystalline Fe3O4/CoO layers at 10 K after 20 kOe field cooling, and was attributed to the strong exchange coupling formed by the interfacial spins between the polycrystalline Fe3O4 and the CoO layer. It was found that at 10 K, the magnetic-moment difference (ΔM) between the zero field cooling curves and field cooling curves first increases and then decreases with the change of the field, and it reaches the maximum value at a field of 20 kOe, which suggests that the interfacial spins can be tuned by the cooling field. Furthermore, other magnetic properties, including field dependence, temperature dependence, and training effects, were investigated, which further confirmed that the interfacial spins play an important role in the EB effect.

Spongy -Toluenesulfonic Acid-doped Polypyrrole with Extraordinary Rate Performance as Durable Anodes of Sodium-Ion Batteries at Different Temperatures.

Sodium-ion batteries (SIBs) have potential as an energy storage system because they have similar electrochemical properties as lithium-ion batteries, abundant resource reserves, and extremely high safety performance. Compared with traditional graphite materials, conductive polymers are more suitable as an anode electrode material for SIBs. In this study, a simple and scalable approach has been used to synthesize -toluenesulfonic acid-doped polypyrrole (p-TSA-PPy).

Improved magnetostriction in Galfenol alloys by aligning crystal growth direction along easy magnetization axis.

Galfenol (Iron-gallium) alloys have attracted significant attention as the promising magnetostrictive materials. However, the as-cast Galfenols exhibit the magnetostriction within the range of 20-60 ppm, far below the requirements of high-resolution functional devices. Here, based on the geometric crystallographic relationship, we propose to utilize the 90°-domain switching to improve the magnetostriction of Galfenols by tuning the crystal growth direction (CGD) along the easy magnetization axis (EMA).

Giant Vertical Magnetization Shift Caused by Field-Induced Ferromagnetic Spin Reconfiguration in NiMnGa Alloy.

Vertical magnetization shift (VMS) is a special type of exchange bias effect that may lead to a revolution in future ultrahigh-density magnetic recording technology. However, there are very few reports focusing on the performance of VMS due to the unclear mechanism. In this paper, a giant vertical magnetization shift (M) of 6.

Machine Learning Magnetic Parameters from Spin Configurations.

Hamiltonian parameters estimation is crucial in condensed matter physics, but is time- and cost-consuming. High-resolution images provide detailed information of underlying physics, but extracting Hamiltonian parameters from them is difficult due to the huge Hilbert space. Here, a protocol for Hamiltonian parameters estimation from images based on a machine learning (ML) architecture is provided.

Cobalt vacancies assisted ion diffusion in CoAlO carbon nanofibers for enhancing lithium battery performance.

The rational design of one-dimensional nanofibers, concentrating on the compositions, morphology, structure and defects, has emerging importance in the preparation of anode materials with desired performance for lithium-ion batteries. In the present work, we prepared cobalt vacancies enriched CoAlO/carbon nanofibers coated with CoAlO nanosheets by using electrospinning and multi-step sintering processes. As the anode of the lithium-ion battery, the as-prepared nanofibers show excellent cycling stability, and particularly the discharge capacity can remain at 627.

Crystal structures and phase relationships in magnetostrictive Tb Dy Co system.

The crystal structures and phase relationships of Tb Dy Co alloys with 0  ⩽  x  ⩽  1 were investigated by synchrotron-based high-resolution x-ray powder diffraction. Three different crystal structures are observed in the system: all the compositions show cubic structure with space group [Formula: see text] at temperatures above the Curie temperature T the Tb-rich side sample shows a rhombohedral structure with space group [Formula: see text] and the Dy-rich side sample has a tetragonal [Formula: see text] space group. In situ measurements on the intermediate compound TbDyCo show a rhombohedral to tetragonal structural transition, and the two phases coexist from 99 K to 111 K, where the so-called magnetic morphotropic phase boundary (MPB) is found.

Thermal Expansion and Magnetostriction of Laves-Phase Alloys: Fingerprints of Ferrimagnetic Phase Transitions.

The magneto-elastic coupling effect correlates to the changes of moment and lattice upon magnetic phase transition. Here, we report that, in the pseudo-binary Laves-phase TbDyCo system ( = 0.0, 0.

The Phase Diagram and Exotic Magnetostrictive Behaviors in Spinel Oxide Co(FeAl)O System.

We report the magnetic and magnetostrictive behaviors of the pseudobinary ferrimagnetic spinel oxide system (1-)CoFeO-CoAlO [Co(FeAl)O], with one end-member being the ferrimagnetic CoFeO and the other end-member being CoAlO that is paramagnetic above 9.8 K. The temperature spectra of magnetization and magnetic susceptibility were employed to detect the magnetic transition temperatures and to determine the phase diagram of this system.

Zero-thermal-hysteresis magnetocaloric effect induced by magnetic transition at a morphotropic phase boundary in Heusler NiMnSbIn alloys.

With the development of magnetic refrigerant technology, magnetic substances with a large magnetocaloric effect (MCE) and nearly zero thermal hysteresis are desired. Although Ni-Mn based Heusler alloys have been found to produce large MCEs and have attracted increasing attention recently, the occurrence of thermal hysteresis accompanying MCE due to the nature of first-order phase transition limits its applications with magnetic refrigeration. Up to now, an effective theory or method to eliminate this thermal hysteresis is still lacking.

Large magnetocaloric effect and near-zero thermal hysteresis in the rare earth intermetallic Tb Dy Co compounds.

We report the magnetocaloric effect in a Tb Dy Co compound which exhibits a wide working temperature window around the Curie temperature (T ) and delivers a large refrigerant capacity (RC) with near-zero thermal hysteresis. Specifically, the wide full width at half maxima ([Formula: see text]) can reach up to 62 K and the RC value changes from 216.5 to 274.

Giant spontaneous exchange bias triggered by crossover of superspin glass in Sb-doped Ni50Mn38Ga12 Heusler alloys.

A spontaneous exchange bias (SEB) discovered by Wang et al. [Phys. Rev.