Fate of Half-Metallicity Near Interfaces: The Case of NiMnSb/MgO and NiMnSi/MgO

Zhang, Ruijing; Eckern, Ulrich; Schwingenschlögl, Udo

doi:10.1021/am5037753

Cited by 9 publications

(7 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…0.5 eV for NiMnSb and 1 eV for CoMnSb) 21 are promising for the development of high-performance magnetoresistive devices owing to the suppression of thermal activations of the electrons above the bandgap. Nevertheless, previous studies have demonstrated that the half-metallic properties of half-Heusler alloys can be very easily degraded by disordering and the presence of defects and/or surface segregation and termination atoms 22 23 24 , and a few percent CPP-GMR ratio was only observed at low temperature (4.2 K) in a polycrystalline NiMnSb/Cu/NiFe system 25 . This indicates that a precise control over the ordering and structure of half-Heusler alloys is highly desired.…”

mentioning

confidence: 99%

Fully epitaxial C1b-type NiMnSb half-Heusler alloy films for current-perpendicular-to-plane giant magnetoresistance devices with a Ag spacer

Wen

Kubota

Yamamoto

et al. 2015

Sci Rep

View full text Add to dashboard Cite

Remarkable magnetic and spin-dependent transport properties arise from well-designed spintronic materials and heterostructures. Half-metallic Heusler alloys with high spin polarization exhibit properties that are particularly advantageous for the development of high-performance spintronic devices. Here, we report fully (001)-epitaxial growth of a high-quality half-metallic NiMnSb half-Heusler alloy films, and their application to current-perpendicular-to-plane giant magnetoresistance (CPP-GMR) devices with Ag spacer layers. Fully (001)-oriented NiMnSb epitaxial films with very flat surface and high magnetization were prepared on Cr/Ag-buffered MgO(001) single crystalline substrates by changing the substrate temperature. Epitaxial CPP-GMR devices using the NiMnSb films and a Ag spacer were fabricated, and room-temperature (RT) CPP-GMR ratios for the C1b-type half-Heusler alloy were determined for the first time. A CPP-GMR ratio of 8% (21%) at RT (4.2 K) was achieved in the fully epitaxial NiMnSb/Ag/NiMnSb structures. Furthermore, negative anisotropic magnetoresistance (AMR) ratio and small discrepancy of the AMR amplitudes between RT and 10 K were observed in a single epitaxial NiMnSb film, indicating robust bulk half metallicity against thermal fluctuation in the half-Heusler compound. The modest CPP-GMR ratios could be attributed to interface effects between NiMnSb and Ag. This work provides a pathway for engineering a new class of ordered alloy materials with particular emphasis on spintronics.

show abstract

mentioning

confidence: 99%

Fully epitaxial C1b-type NiMnSb half-Heusler alloy films for current-perpendicular-to-plane giant magnetoresistance devices with a Ag spacer

Wen

Kubota

Yamamoto

et al. 2015

Sci Rep

View full text Add to dashboard Cite

show abstract

“…Using DFT calculations, a genuine half-metallic interface of NiMnSb with InP and CdS has been obtained only for the anion terminated (111) direction 78 . Interfaces of semi-Heuslers NiMnSb or NiMnSi with large gap insulators such as MgO have been also studied 79 . A high spin polarization has been obtained only under the prerequisite of structural optimization 79 .…”

Section: Discussionmentioning

confidence: 99%

“…Interfaces of semi-Heuslers NiMnSb or NiMnSi with large gap insulators such as MgO have been also studied 79 . A high spin polarization has been obtained only under the prerequisite of structural optimization 79 .…”

Section: Discussionmentioning

confidence: 99%

Spectral properties of heterostructures containing half-metallic ferromagnets in the presence of local many-body correlations

Weh,

Otsuki,

Schnait

et al. 2020

Preprint

View full text Add to dashboard Cite

In this work, we investigate models for bulk, bi-and multilayers containing half-metallic ferromagnets (HMFs), at zero and at finite temperature, in order to elucidate the effects of strong electronic correlations on the spectral properties (density of states). Our focus is on the evolution of the finite-temperature many-body induced tails in the half-metallic gap. To this end, the dynamical mean-field theory (DMFT) is employed. For the bulk, a Bethe lattice model is solved using a matrix product states based impurity solver at zero temperature and a continuous-time quantum Monte Carlo (CT-QMC) solver at finite temperature. We demonstrate numerically, in agreement with the analytical result, that the tails vanish at the Fermi level at zero temperature. In order to study multilayers, taken to be square lattices within the layers, we use the real-space DMFT extension with the CT-QMC impurity solver. For bilayers formed by the HMF with a band or correlated insulator, we find that charge fluctuations between the layers enhance the finite temperature tails. In addition, in the presence of inter-layer hopping, a coherent quasiparticle peak forms in the otherwise correlated insulator. In the multilayer heterostructure setup, we find that by suitably choosing the model parameters, the tails at the HMF/Mott insulator interface can be reduced significantly, and that a high spin polarization is conceivable, even in the presence of long-ranged electrostatic interactions.

show abstract

“…36 Past research reports claimed that half-metallicity in half-Heusler alloys strongly depends on the structural ordering, defects, and surface segregation and termination atoms. 38,39 Structural ordering also has an impact on other magnetic properties as well. Epitaxial growth of Heusler alloys that are co-related with deposition temperature is really crucial for a stable crystal structure like the C1 b -type NiMnSb thin film.…”

Section: Introductionmentioning

confidence: 99%

Nanoscale-Thick Ni-Based Half-Heusler Alloys with Structural Ordering-Dependent Ultralow Magnetic Damping: Implications for Spintronic Applications

Mandal

Kurniawan

Suzuki

et al. 2022

ACS Appl. Nano Mater.

View full text Add to dashboard Cite

Atomic ordering and its consequence on the crystal structure are fundamental issues in the application of half-metallic Heusler alloys considered as a high spin-polarized electron source. NiMnSb is a promising half-metallic half-Heusler alloy for spintronic devices due to its low magnetic damping, noncentrosymmetric crystal structure, and rich anisotropies. Here, we report a highquality half-metallic epitaxial nano-scale thick NiMnSb alloy film grown on a Cr/ Ag-buffered MgO (001) single crystalline substrate. High temperature deposition is a crucial parameter for crystal growth and magneto-dynamic properties such as damping, anisotropy, magnetization, etc. After investigating the ferromagnetic resonance (FMR) spectroscopy using a time-resolved magneto-optical Kerr (TRMOKE) microscope and calculating the crystal structure using VESTA and the density of states from first-principles calculations, we discuss how the deposition temperature influences the crystal ordering, damping, and magnetization. Ultralow Gilbert damping with high anisotropic field and saturation magnetization were found for the highly ordered C1 b structured nanoscale thick NiMnSb film deposited at 573 K. We also found quite nice agreement between theoretical and experimental data of crystal ordering and damping that explains how the ordering affects the magnetic parameter as well as sample quality. Furthermore, the negative anisotropic magnetoresistance ratio implies the robust bulk half-metallicity. Such unique combination of highly ordered half-metallic NiMnSb alloy in the nano-scale regime with ultralow damping can be regarded as an advantage for applications in spintronic devices.

show abstract

Fate of Half-Metallicity Near Interfaces: The Case of NiMnSb/MgO and NiMnSi/MgO

Cited by 9 publications

References 19 publications

Fully epitaxial C1b-type NiMnSb half-Heusler alloy films for current-perpendicular-to-plane giant magnetoresistance devices with a Ag spacer

Fully epitaxial C1b-type NiMnSb half-Heusler alloy films for current-perpendicular-to-plane giant magnetoresistance devices with a Ag spacer

Spectral properties of heterostructures containing half-metallic ferromagnets in the presence of local many-body correlations

Nanoscale-Thick Ni-Based Half-Heusler Alloys with Structural Ordering-Dependent Ultralow Magnetic Damping: Implications for Spintronic Applications

Contact Info

Product

Resources

About