- Growth and magnetic properties of epitaxial MnAs thin films grown on InP(001)
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Epitaxial ferromagnetic MnAs thin films have been grown by molecular-beam epitaxy on semi-insulating InP(001) substrates. The MnAs c axis (MnAs[0001]) lies along the InP[110] axis, and the easy magnetization axis is in-plane, along the MnAs[1120] axis, which is parallel to the InP[110] axis. The ferromagnetic transition temperature of the MnAs films on InP(001) was estimated to be 321 K. The structural and magnetic properties of MnAs thin films grown on InP(001) substrates are similar to those of type-A MnAs films grown on GaAs(001) substrates. The feasibility of growing monocrystalline ferromagnetic layers on InP(001) will open up the possibility of monolithic integration of magnetic functions with InP-based optoelectronics devices.
- Yokoyama,Ohya,Tanaka
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- Growth and characterization of ferromagnetic MnAs films on different semiconductor substrates
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MnAs thin films were grown by metalorganic vapour-phase epitaxy (MOVPE) on GaAs(0 0 1), Si(0 0 1) and oxidised silicon substrates. All films are crystalline and contain only the ferromagnetic α-MnAs phase. X-ray diffraction (XRD) and atomic force microscopy (AFM) measurements show that films on GaAs(0 0 1) have strong preferential orientation, developing elongated grains parallel to [1 -1 0] GaAs while films on bare and oxidised Si are polycrystalline with irregular-shaped, randomly oriented grains. Magneto-optic Kerr effect (MOKE) measurements show good magnetic properties for films on GaAs, such as strong in-plane anisotropy and squareness of the hysteresis loop in the easy direction. A Curie temperature of 340 K, remarkably higher than the bulk material (315 K), was found for a 65 nm thick film on GaAs. Films grown on bare and oxidised silicon wafers had lower Curie temperature and were magnetically isotropic.
- Bolzan,Bergenti,Rossetto,Zanella,Dediu,Natali
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- State diagram of the Zn3As2-MnAs system
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The Zn3As2-MnAs system was studied by X-ray powder diffraction, differential thermal, and microstructural analyses. This system is of the eutectic type with the eutectic coordinates (30 wt % (50 mol %) Zn3As2, 70 wt % (50 mol %) MnAs, T melt = 815°C). The MnAs solubility boundary on the side of Zn3As2 is 10 wt %. Zn3As2 alloys containing more than 10 wt % MnAs are ferromagnetic with T c ~ 320 K. Their magnetization increases with increasing MnAs content.
- Marenkin,Fedorchenko,Trukhan,Trukhanov,Shoukavaya,Vasil'Ev,Zhaludkevich
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- Synthesis of Ferromagnetic Alloys Semiconductor–Ferromagnet in the CdAs2–MnAs System
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Abstract: Semiconductor–ferromagnet alloys in the CdAs2–MnAs system were synthesized in evacuated ampules. Differential thermal analysis (DTA), X-ray powder diffraction analysis, differential scanning calorimetry, and scanning electron microscopy showed that this system is eutectic (of the acicular type), and the coordinates of the eutectic are (6 ± 0.5 mol % MnAs, Tmelt = 614 ± 1°C). The liquidus lines constructed based on the thermal events of melting in DTA are 40–50°C higher than the lines constructed based on the thermal events of crystallization, which is due to the tendency of CdAs2 toward glass transition. The synthesized alloys are ferromagnetic with TC = 315 K, and the magnetization of them increases with increasing MnAs content. The alloys with nanoinclusions ≤40 nm of the ferromagnetic phase MnAs were produced by crystallization from melts at high cooling rates (≤100 deg/s). They have a higher Curie temperature of TC = 353 K and a negative magnetoresistance of ΔR = 2% at 300 K in a saturation magnetic field of 4500 Oe, which is of practical interest for creating magnetic granular spintronic structures.
- Fedorchenko, I. V.,Kozlov, V. V.,Marenkin, S. F.,Ril’, A. I.
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- First-order phase transition at the curie temperature in MnAs and MnAs 0.9Sb0.1
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Structural transformations of MnAs and MnAs0.9Sb0.1 were investigated by X-ray diffraction in high magnetic fields up to 5 T. The temperature dependence of the magnetization was measured in a magnetic field of 0.01 T and the Curie temperature TC was determined to be 315 K for MnAs and 290 K for MnAs0.9Sb0.1 during heating process. For both compounds, a metamagnetic transition from a paramagnetic to a ferromagnetic state was observed above TC. The X-ray diffraction profile at 319 K for MnAs showed a single phase of an orthorhombic MnP-type structure in zero field. An applied magnetic field of 3 T induced the appearance of a hexagonal NiAs-type structure. On further increase of the magnetic field, a single phase with a hexagonal structure was realized above 3.5 T in a forced-ferromagnetic state. The X-ray diffraction profile at 295 K for MnAs 0.9Sb0.1 showed a hexagonal NiAs-type structure. The coexistence of ferromagnetic and paramagnetic states with different lattice parameters was confirmed in a magnetic field of 2.5 T. The volume expansion induced by a magnetic field was found to be 2.1% for MnAs and 1.1% for MnAs 0.9Sb0.1. 2006 The Physical Society of Japan.
- Ishikawa, Fumihiro,Koyama, Keiichi,Watanabe, Kazuo,Asano, Tetsuya,Wada, Hirofumi
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- Formation of nanoscale ferromagnetic MnAs crystallites in low-temperature grown GaAs
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We report the formation of nanosize ferromagnetic MnAs crystallites imbedded in low-temperature grown GaAs using Mn+ ion implantation and subsequent annealing. The structural and magnetic properties of the crystallites have been characterized b
- Wellmann,Garcia,Feng,Petroff
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- Magnetic out-of-plane component in MnAs/GaAs(001)
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The magnetic out-of-plane component in MnAs/GaAs film was discussed. Its temperature dependence was substantially different from the dominating in-plane magnetization. The analysis showed that the out-of-plane component was due to small isolated magnetic
- Ney,Hesjedal,Pampuch,Mohanty,Das,Daeweritz,Koch,Ploog
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- NUCLEAR MAGNETIC RESONANCE OF 55Mn AND 75As IN MnAs.
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Four sets of NMR signals, two each, from **5**5Mn and **7**5As nuclei have been observed. The temperature dependences of **5**5Mn resonances have been studied from 77 to 311 K and that of **7**5As, from 77 K to about 250 K. The results show that there is a phase transition at T//1 approximately equals 220 K. This transition may be due to introduction of a local spontaneous distortion in the region of the domain walls in the lattice, resulting in lowering of symmetry at low temperatures. Another possibility is the canting of spins which would lower the magnetic group symmetry.
- Pinjare,Rao
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- Schottky barrier height of ferromagnet/Si(001) junctions
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The Schottky barrier height of ferromagnetic metal/semiconductor junctions is one of the most important parameters for the performance of semiconductor-based spin-electronic devices. The authors investigated the Schottky barrier height φB of ferromagnet/Si(001) junctions with various ferromagnetic metals (CoFe, CoFeB, and MnAs), and found that φB of epitaxial MnAs/Si(001) junctions fabricated by molecular beam epitaxy was 0.16 eV for electrons, which is much lower than φB (~0.7 eV) of CoFe/Si(001) and CoFeB/Si(001) junctions. This implies that MnAs is a promising ferromagnetic material for Si-based spin-electronic devices, especially for the source and drain of spin metal-oxide-semiconductor field effect transistors.
- Sugiura, Kuniaki,Nakane, Ryosho,Sugahara, Satoshi,Tanaka, Masaaki
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- Carbon-doping effects on the metamagnetic transition and magnetocaloric effect in MnAsCx
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Carbon doping effects in MnAs alloys have been investigated. More carbon doping in MnAs alloys leads to lower Curie temperature, larger thermal hysteresis and sharper slope of the dependence of critical field on reduced temperature due to severe lattice distortion. The obtained maximum of magnetic entropy change for a field change of 5 T is about 12.8 J kg-1 K-1 near room temperature, and increases with more doping carbon content to about 22.4 J kg-1 K-1 in MnAsC0.03 and 13.2 J kg-1K-1 in MnAsC0.05.
- Cui,Liu,Zhang,Li,Liu,Yang,Zhao,Zhang
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- X-ray diffraction study of the structural phase transition in MnAs under high magnetic fields
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The structural phase transition induced by magnetic fields on MnAs was observed by the X-ray diffraction measurements in high magnetic fields up to 4 T. Magnetization measurements showed that Curie temperature TC was 315.5 K for increasing temperatures and a metamagnetic transition from the paramagnetic to the ferromagnetic state occurred above TC. The structural transformation from the hexagonal NiAs-type to the orthorhombic MnP-type structure was confirmed at TC with increasing temperature from 290 to 319 K via two-phase coexistence region. The X-ray diffraction profiles at 319 K showed the single phase of the MnP-type structure in zero field and applying magnetic field of 3 T caused appearance of the Brag peak of the hexagonal structure. On further increase of magnetic fields, the single phase of the hexagonal structure was observed above 3.5 T in the forced ferromagnetic state. Both the magnetic and structural transitions induced by magnetic fields above TC were first order with a hysteresis and had a close relationship between each other.
- Ishikawa, Fumihiro,Koyama, Keiichi,Watanabe, Kazuo,Wada, Hirofumi
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- Giant magnetocaloric effect of MnAs1-xSbx
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A giant magnetocaloric effect was found in MnAs, which undergoes a first-order ferromagnetic to paramagnetic transition at 318 K. The magnetic entropy change caused by a magnetic field of 5 T is as large as 30 J/K kg at the maximum value, which exceeds that of conventional magnetic refrigerant materials by a factor of 2-4. The adiabatic temperature change reaches 13 K in a field change of 5 T. The substitution of 10% Sb for As reduces the thermal hysteresis and lowers the Curie temperature to 280 K, while the giant magnetocaloric properties are retained.
- Wada,Tanabe
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- Formation of the α''-phase and study of the solubility of Mn in Cd3As2
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We studied the effect of Mn on the structure and properties of Cd3?xMnxAs2 crystals with x = 0–0.24, synthesized by direct fusion of high-purity elements. Obtained X-ray diffraction patters suggest that the incorporation of Mn promotes a structural phase transition from primary α-Cd3As2 (x = 0) phase to the α''– Cd3As2 (x = 0.24) phase, while at intermediate compositions both phases can coexist. In addition, the increase of Mn content results in the decrease of lattice cell parameters, which effectively saturates for x > 0.13. Microstructural, calorimetric and magnetometry studies suggest that at high Mn content (x = 0.24) secondary MnAs phase appears. Using obtained results, we estimated the solubility limit of Mn in Cd3As2 as x~0.13, which corresponds to the formation of ternary Cd3?xMnxAs2 compound where Cd atoms are partially substituted by Mn. Formation of ternary compound was also suggested by the results for Cd3As2 + MnAs composite systems, where we also observed the presence of CdAs2 phase, which is a byproduct of corresponding reaction. Additional studies suggested that the CdAs2 phase formation in composite system can be prevented if one uses the Cd3?xMnxAs2 compound instead of pure Cd3As2 as a matrix material.
- Ril,Marenkin,Volkov,Oveshnikov,Kozlov
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supporting information
(2021/10/04)
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- ThMnPnN (Pn = P, As): Synthesis, Structure, and Chemical Pressure Effects
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Mn-based ZrCuSiAs-type pnictides ThMnPnN (Pn = P, As) containing PbO-type Th2N2 layers were synthesized. The crystal and magnetic structures are determined using X-ray and neutron powder diffraction. While neutron diffraction indicates a C-type antiferromagnetic state at 300 K, the temperature dependence of the magnetic susceptibility shows cusps at 36 and 52 K respectively for ThMnPN and ThMnAsN. The susceptibility cusps are ascribed to a spontaneous antiferromagnetic-to-antiferromagnetic transition for Mn2+ moments, which is observed for the first time in Mn-based ZrCuSiAs-type compounds. In addition, measurements of the resistivity and specific heat suggest an abnormal increase in the density of states at the Fermi energy. The result is discussed in terms of the internal chemical pressure effect.
- Cao, Guang-Han,Feng, Zhifa,Hu, Bingfeng,Jing, Qiang,Li, Baizhuo,Liu, Bo,Liu, Zichen,Luo, Huiqian,Ma, Jie,Mao, Huican,Mei, Yuxue,Ren, Qingyong,Ren, Zhi,Shao, Yeting,Sun, Yuping,Tan, Shugang,Wang, Cao,Wang, Zhicheng,Xia, Yuanhua,Zhang, Fuxiang
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- Exotic Compositional Ordering in Manganese–Nickel–Arsenic (Mn-Ni-As) Intermetallics
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In this work we benefited from recent advances in tools for crystal-structure analysis that enabled us to describe an exotic nanoscale phenomenon in structural chemistry. The Mn0.60Ni0.40As sample of the Mn1?xNixAs solid solution, exhibits an incommensurate compositional modulation intimately coupled with positional modulations. The average structure is of the simple NiAs type, but in contrast to a normal solid solution, we observe that manganese and nickel segregate periodically at the nano-level into ordered MnAs and NiAs layers with thickness of 2–4 face-shared octahedra. The detailed description was obtained by combination of 3D electron diffraction, scanning transmission electron microscopy, and neutron diffraction. The distribution of the manganese and nickel layers is perfectly described by a modulation vector q=0.360(3) c*. Displacive modulations are observed for all elements as a consequence of the occupational modulation, and as a means to achieve acceptable Ni–As and Mn–As distances. This modulated evolution of magnetic MnAs and non-magnetic NiAs-layers with periodicity at approximately 10 ? level, may provide an avenue for spintronics.
- Fjellv?g, ?ystein Slagtern,Fjellv?g, Helmer,Gonano, Bruno,Pelloquin, Denis,Saha, Dipankar,Steciuk, Gwladys
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supporting information
p. 22382 - 22387
(2020/10/15)
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- Phase diagram of ZnAs2–MnAs system
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The ZnAs2–MnAs system, characterized by X-ray powder diffraction, differential thermal and microstructure studies, is of the eutectic type, with the coordinates of eutectic 73 mol% ZnAs2 and 27 mol% MnAs and Tm = 716 °C. T
- Marenkin, Sergey F.,Ril, Alexey I.,Fedorchenko, Irina V.
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p. 219 - 221
(2018/03/26)
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- Composition and structural perfection of (AIII,Mn)BV and MnBV (A = Ga, In; B = Sb, As, P) nanolayers
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We have determined the elemental composition of laser-deposited (Ga,Mn)Sb, (In,Mn)As, MnP, MnAs, and MnSb layers. The InMnAs layers were not single-phase and contained MnAs clusters. Active Ga and Mn diffusion to the substrate and arsenic diffusion from the substrate during the GaMnSb growth process is accompanied by the formation of a GaMnAs intermediate layer. Pleiades Publishing, Ltd., 2012.
- Dunaev,Zvonkov,Danilov,Vikhrova,Drozdov,Drozdov,Suchkov
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p. 553 - 558
(2012/07/13)
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- Studies on effects of impurity doping and NMR measurements of La 1111 and/or Nd 1111 Fe-Pnictide superconductors
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Measurements of the electrical resistivity ρ, Hall coefficient R H, thermoelectric power S, and the electronic specific heat coefficient γ have been carried out for samples of LnFe 1-yMyAsO1-xFx (Ln = La, Nd; M = Co, Mn; x = 0:11) obtained by doping M atoms into the superconducting LnFeAsO 1-xFx (Ln 1111) system. The NMR longitudinal relaxation rate 1/T1 has also been measured for samples of LnFe 1-yMyAsO1-xFx with various x values. Co atoms doped into the superconducting LnFeAsO1-xFx are nonmagnetic, and the rate of Tc-suppression |dTc/dx| by Co atoms has been found to be too small to be explained by the pair-breaking effect expected for the S± superconducting symmetry proposed as the most probable symmetry for the system. This result throws a serious doubt on whether the symmetry is realized in the system. Instead of the pair breaking, two mechanisms of Tc suppression by the doped impurities have been found: One is the electron localization, which appears when the sheet resistance R□ exceeds h/4e2 = 6:45 kΩ, and the other is the disappearance (or reduction in the area) of the hole Fermi surfaces around the Γ point in the reciprocal space. The latter mechanism has been observed when the number of electrons increases with increasing Co doping level and the system changes from an anomalous metal to an ordinary one. Regarding the two distinct T dependences of the NMR longitudinal relaxation rate 1/T 1 of LaFeAsO1-xFx, (1=T1 ∝ T6 reported by our group in the T region from Tc to ~0:4 Tc for samples with the highest Tc values with varying x, and 1/T1 ∝ T2:5-3:0 observed by many groups in almost the entire T region studied below Tc), we discuss the origin of such a difference, and show that, at least, the T2:5-3:0-like dependence of 1/T1 cannot be considered as the experimental evidence for the S± symmetry of δ.
- Sato, Masatoshi,Kobayashi, Yoshiaki,Lee, Sang Chul,Takahashi, Hidefumi,Satomi, Erika,Miura, Yoko
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- Transition Metal Pnictide Synthesis: Self Propagating Reactions Involving Sodium Arsenide, Antimonide and Bismuthide
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Initiation of the reaction between Na3E (E=As, Sb, Bi) and anhydrous metal halides at 25 to 550 deg C produces metal arsenides MxAsy (M = Y, La, Ti, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Pt, Cu and Zn) and antimonides MxSby (M = Ti, V, Nb, Ta, Cr, Fe, Co, Ni, Pt, Cu and Zn) via an exothermic selfpropagating reaction.The metal arsenides were characterized by X-ray powder diffraction, SEM/EDAX, microanalysis and FT-IR. - Keywords: Metal Arsenide, Sodium Arsenide, Metal Antimonide, Sodium Antimonide, Solid State Methathesis
- Hector, Andrew L.,Parkin, Ivan P.
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p. 477 - 482
(2007/10/02)
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- ON THE MnP reversible reaction NiAs-TYPE TRANSITION IN Mn0. 63Cr0. 37As: STRUCTURAL AND THERMODYNAMIC PROPERTIES.
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The displacive MnP reversible reaction NiAs-type structural transition and the coupled magnetic spin conversion in Mn//0//. //6//3Cr//0//. //3//7As have studied by adiabatic shield type calorimetry and by powder X-ray and neutron diffraction. The structur
- Fjellvag,Gronvold,Kjekshus,Stolen
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p. 355 - 363
(2008/10/08)
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- DOUBLE EXCHANGE IN CrxMn1 - xAs COMPOUNDS.
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The magnetic moment M and the specific resistivity rho are measured for temperatures between 5 and 300 K and for eight different compositions. Characteristic temperatures are used to construct a magnetic phase diagram. The magnetic phases between ferromagnetic MnAs and antiferromagnetic CrAs are explained on the basis of two competing superexchange-double exchange magnetic couplings.
- Woehl,Berg,Baerner
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p. 179 - 190
(2008/10/08)
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