arXiv subjects

Ze-Jin Yang

Publications and source records attributed to Ze-Jin Yang.

4 recordsLinked to original sources

arXiv2023

Predicting synthesizable manganese nitride with unprecedentedly giant magnetocrystalline anisotropy energy

Using modern crystal structure prediction program (CALYPSO), we searched many experimentally synthesizable low-energy structures with perfect or nearly perfect easy-axis magnetocrystalline anisotropy energy (MAE) in manganese nitride, including MnN, Mn2N, Mn3N2, Mn5N2, Mn4N, respectively, which are the more frequently studied stoichiometries by experimental researchers. MnN ( I-42d) shows giant MAE with values of E001=1006, E010=0, E100=920 ueV/atom (same hereinafter), respectively. One perfect easy-axis MAE in Mn3N2 (P42/mmc) with correspondent values of E010=E100=12 is observed, the other nearly perfect easy-axis MAE one (Ibam) with respective values of E001=324 and E010=345 is observed. Four almost totally perfect easy-axis MAE structures are obtained in Mn2N, including P4/mmm with individual E001=249 and E100=250, Pccm with E001=E100=62, P4/nmm with E001=58 and E100=60, Imma with E001=108 and E100=109, respectively. Three structures including one perfect candidates are found in Mn4N, including Fmmm with individual E001=126 and E010=121, I4/mmm with E010=127 and E100=133, I4/mmm with E001= E100=169, respectively. Too many valuable structures are deserved to be further studied by both theoretical and experimental scientists. The present study might attract close attention to these several compounds.

physics.app-ph↗

arXiv2021

Predicting synthesizable cobalt and manganese silicides, germanide with desirable magnetic anisotropy energy

The nanoparticle Co3Si (P63/mmc) displays remarkable magnetism [Appl. Phys. Lett. 108, 152406 (2016)], we thus searched cobalt silicides and several phases are searched including a Cmcm with 60 meV/atom lower than that of P63/mmc. A lower-energy Co R3m (-7.03 eV/atom) is predicted, whose energy is higher than that of known P63/mmc (-7.04 eV/atom) but is lower than that of Fm3m (-7.02 eV/atom). Three small-magnetism low-energy Fe5Si3 structures are searched with energies 30 meV/atom lower than that of experimental P63/mcm. The strong lattice shape dependence of magnetocrystalline anisotropy energy (MAE) is studied through X5Si3 (X=Mn, Fe, Co). The building-block shape and energy order of cobalt silicide is dominated by Co P63/mmc, Fm3m , R3m , respectively. The Co3C and Co3Sn have positive formation of energy, thus only Co3Ge has similar structures with those of counterparts of Co3Si. Several low-energy perfect or nearly-perfect easy-axis/plane MAE Mn3Si, Mn5Si2, and Mn5Si3 structures are searched and present important application, as is also the case in Ge-containing counterparts. A structure I4122 with energy 300 meV/atom lower than that of experimental Mn5Si3 P63/mcm is searched

cond-mat.mtrl-sci↗

arXiv2020

Novel structural evolution of several nanolaminate Mn+1AXn (n=1, 2, 3, etc.) ceramics under pressure from first principles

We did extensive research for the typical nanolaminate Mn+1AXn (n=1, 2, 3) ceramics focusing on the structural stability, the phase transition pressure of Ti2GaN (160 GPa) is far higher than that of Zr2GaN (92 GPa), meaning the strong M dependence of the same group, whereas Zr2AlN (98 GPa) has similar value with that of Zr2GaN, meaning the weak A dependence. Mo2GaC shows lowest phase transition pressure among all of the known MAX, meaning that C-containing phase has lower phase transition pressure than that of N-containing counterparts. All of the metastable phases of the selected MAX transition almost at the same time, such as all of the metastable phases of Zr2AlN transition at the similar pressure, about 90-110 GPa, with a very narrow pressure range of less than 20 GPa, as is also the case for Zr2GaN corresponding to 90-115 GPa and for Mo2GaC corresponding to 10-25 GPa. Mo2GaC presents multi-phase co-existence status at high pressure, whose P63/mmc alpha-beta phase transition is the more commonly and frequently occurred route in this kind of MAX structure. The hexagonal P63-mmc to tetragonal P4-mmm transition is the common direct route for the N-containing MAX due probably to the high transition pressure. P63/mmc alpha-beta-P4-mmm transition might be the common route for the C-containing MAX due probably to the low alpha-beta transition pressure. Nb2InN(Nb2GaN) and Mo2InN present c-axis abnormal elongation at low pressures, these compounds have negative formation of energy at ambient conditions, meaning that all of them are stable or experimentally synthesizeable.

cond-mat.mtrl-sci↗

arXiv2016

Asymmetric angular dependence of spin-transfer torques in CoFe/Mg-B-O/CoFe magnetic tunnel junctions

Using a first-principles noncollinear wave-function-matching method, we studied the spin-transfer torques (STTs) in CoFe/Mg-B-O/CoFe(001) magnetic tunnel junctions (MTJs), where three different types of B-doped MgO in the spacer are considered, including B atoms replacing Mg atoms (Mg$_3$BO$_4$), B atoms replacing O atoms (Mg$_4$BO$_3$), and B atoms occupying interstitial positions (Mg$_4$BO$_4$) in MgO. A strong asymmetric angular dependence of STT can be obtained both in ballistic CoFe/Mg$_3$BO$_4$ and CoFe/Mg$_4$BO$_4$ based MTJs, whereas a nearly symmetric STT curve is observed in the junctions based on CoFe/Mg$_4$BO$_3$. Furthermore, the asymmetry of the angular dependence of STT can be suppressed significantly by the disorder of B distribution. Such skewness of STTs in the CoFe/Mg-B-O/CoFe MTJs could be attributed to the interfacial resonance states induced by the B diffusion into MgO spacer. The present investigation demonstrates the feasibility of effectively enhancing microwave output power in MgO based spin torque oscillator (STO) by doping the B atoms into MgO spacer.

cond-mat.mes-hall↗