Strain-induced high ferromagnetic transition temperature of MnAs epilayer grown on GaAs (110)

Xu, Pengpeng; Lu, Jun; Chen, Lin; Yan, Shuai; Meng, Hong-Hu; Pan, Guoqiang; Zhao, Jianhua

doi:10.1186/1556-276x-6-125

Cited by 12 publications

(9 citation statements)

References 27 publications

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“…24 As shown in Fig.3b, the 630 o C annealed SLs exhibit a ferromagnetic-like ordering below 350K, again similarly to the single layers studied earlier in the same conditions. 15 Similar high temperature ferromagnetism was observed in (Ga,Mn)As systems containing (Mn,Ga)As nanocrystals with zinc-blende structure 12 as well as, interestingly, in strained single epitaxial layers of MnAs deposited on GaAs (110) 25 and…”

supporting

confidence: 63%

Formation of two-dimensionally confined superparamagnetic (Mn, Ga)As nanocrystals in high-temperature annealed (Ga, Mn)As/GaAs superlattices

Sadowski¹,

Domagała²,

Mathieu³

et al. 2013

J. Phys.: Condens. Matter

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The annealing-induced formation of (Mn,Ga)As nanocrystals in (Ga,Mn)As/GaAs superlattices was studied by X-ray diffraction, transmission electron microscopy and magnetometry. The superlattice structures with 50Å thick (Ga,Mn)As layers separated by 25, 50 and 100Å thick GaAs spacers were grown by molecular beam epitaxy at low temperature (250 o C), and then annealed at high temperatures of: 400, 560 and 630 o C. The high temperature annealing causes decomposition to GaMnAs ternary alloy and formation of (Mn,Ga)As nanocrystals inside the GaAs matrix. The nanocrystals are confined in the planes that were formerly occupied by (Ga,Mn)As layers for up to the 560°C of annealing and diffuse throughout the GaAs spacer layers at 630°Cannealing. The corresponding magnetization measurements show the evolution of the magnetic properties of as-grown and annealed samples from ferromagnetic, through superparamagnetic to the combination of both.

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supporting

confidence: 63%

Formation of two-dimensionally confined superparamagnetic (Mn, Ga)As nanocrystals in high-temperature annealed (Ga, Mn)As/GaAs superlattices

Sadowski¹,

Domagała²,

Mathieu³

et al. 2013

J. Phys.: Condens. Matter

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“…As an estimation of M 0 we take the value of the remanent magnetization of an epitaxial MnAs layer (about 900 G at 270 K [17]). The typical value of the carrier concentration for our InMnAs layers at 270 K is about 3 · 10 18 cm…”

Section: Gaasmentioning

confidence: 99%

Anomalous Hall effect in two-phase semiconductor structures: The role of ferromagnetic inclusions

et al. 2014

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The Hall effect in InMnAs layers with MnAs inclusions of 20-50 nm in size is studied both theoretically and experimentally. We find that the anomalous Hall effect can be explained by the Lorentz force caused by the magnetic field of ferromagnetic inclusions and by an inhomogeneous distribution of the current density in the layer. The hysteretic dependence of the average magnetization of ferromagnetic inclusions on an external magnetic field results in a hysteretic dependence of RH(Hext). Thus we show the possibility of a hysteretic RH(Hext) dependence (i.e. observation of the anomalous Hall effect) in thin conductive layers with ferromagnetic inclusions in the absence of carriers spin polarization.PACS numbers: 61.72.uj, 72.20.My, 75.50.Pp The investigation of the anomalous Hall effect (AHE) is a widely used experimental method for the diagnostics of the magnetic and transport properties of ferromagnetic layers, in particular, those of diluted magnetic semiconductors (DMS) [1]. In the conventional interpretation, the AHE is a consequence of an asymmetric scattering of spin-polarized charge carriers in ferromagnetic materials [2]. Thus the observation of the AHE is traditionally considered to be a proof of the presence of spin-polarized carriers. The spin polarization of carriers in DMS is usually attributed to a mechanism of indirect exchange interaction between transition metal ions via charge carriers [3,4]. In the high temperature region this mechanism should become slack [3,4]. However, the AHE was observed at room temperature or above in some Mn-doped semiconductors [5][6][7]. The AHE was also observed at about 300 K in Co-doped TiO 2 [8,9] and (La,Sr)TiO 3 [10] layers containing Co clusters. In Refs. [8-10] the appearance of AHE was related to spin polarization by extrinsic (induced by the clusters) spin orbit scattering. Earlier, it was also observed that in InMnAs layers obtained by laser deposition in gas atmosphere a clear hysteresis in the magnetic field dependencies of the Hall resistance manifests itself up to room temperature [11].In III-Mn-V layers the second-phase inclusions may appear during technology processes. In particular, nanosize ferromagnetic MnAs particles can be embedded in a semiconductor matrix [12,13] In this Letter, we present the results of theoretical and experimental investigations of the AHE in the InMnAs layers obtained by laser deposition. Nevertheless our results can be generalized to other conductive layers with ferromagnetic inclusions. Figure 1 shows the brightfield cross-sectional scanning transmission electron microscopy (STEM) image of the InMnAs/GaAs structure with Y Mn =0.2. The image reveals a phase inhomogeneity of the InMnAs layer. Figure 1 also shows the energydispersive X-ray spectroscopy (EDS) mapping of Mn, In and As in the structure. The bright areas in the Mn mapping image correspond to the regions of predominantly Mn atoms. At the same time these regions are free from In atoms. Taking into account the uniform distribution of As atoms it can be concluded ...

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“…All of the previous literature reports on GaAs–MnAs hybrids concerned planar samples, with MnAs nanoinclusions embedded in the zinc-blende GaAs thin films. The moderate influence of strain on the magnetic properties of MnAs both in the form of epilayers deposited on, and NCs embedded in the zinc-blende GaAs had already been noticed, but resulted in a moderate increase of T C . − …”

Section: Results and Discussionmentioning

confidence: 87%

“…The moderate influence of strain on the magnetic properties of MnAs both in the form of epilayers deposited on, and NCs embedded in the zinc-blende GaAs had already been noticed, but resulted in a moderate increase of T C . 26,27,28,29 The significance of our experimental findings is 2-fold. First, we show that the Curie temperature in a ferromagnetic metal MnAs can be substantially increased from the textbook 313 K to above 400 K by the adequate nanostructure engineering.…”

Section: Introductionmentioning

confidence: 68%

Enhanced Ferromagnetism in Cylindrically Confined MnAs Nanocrystals Embedded in Wurtzite GaAs Nanowire Shells

et al. 2019

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Nearly a 30% increase in the ferromagnetic phase transition temperature has been achieved in strained MnAs nanocrystals embedded in a wurtzite GaAs matrix. Wurtzite GaAs exerts tensile stress on hexagonal MnAs nanocrystals, preventing a hexagonal to orthorhombic structural phase transition, which in bulk MnAs is combined with the magnetic one. This effect results in a remarkable shift of the magneto-structural phase transition temperature from 313 K in the bulk MnAs to above 400 K in the tensely strained MnAs nanocrystals. This finding is corroborated by the state of the art transmission electron microscopy, sensitive magnetometry, and the first-principles calculations. The effect relies on defining a nanotube geometry of molecular beam epitaxy grown core−multishell wurtzite (Ga,In)As/(Ga,Al)As/(Ga,Mn)As/GaAs nanowires, where the MnAs nanocrystals are formed during the thermal-treatment-induced phase separation of wurtzite (Ga,Mn)As into the GaAs−MnAs granular system. Such a unique combination of two types of hexagonal lattices provides a possibility of attaining quasi-hydrostatic tensile strain in MnAs (impossible otherwise), leading to the substantial ferromagnetic phase transition temperature increase in this compound.

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Strain-induced high ferromagnetic transition temperature of MnAs epilayer grown on GaAs (110)

Cited by 12 publications

References 27 publications

Formation of two-dimensionally confined superparamagnetic (Mn, Ga)As nanocrystals in high-temperature annealed (Ga, Mn)As/GaAs superlattices

Formation of two-dimensionally confined superparamagnetic (Mn, Ga)As nanocrystals in high-temperature annealed (Ga, Mn)As/GaAs superlattices

Anomalous Hall effect in two-phase semiconductor structures: The role of ferromagnetic inclusions

Enhanced Ferromagnetism in Cylindrically Confined MnAs Nanocrystals Embedded in Wurtzite GaAs Nanowire Shells

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