All-Wurtzite (In,Ga)As-(Ga,Mn)As Core–Shell Nanowires Grown by Molecular Beam Epitaxy

Siusys, Aloyzas; Sadowski, J.; Sawicki, M.; Kret, S.; Wojciechowski, Tomasz; Gas, Katarzyna; Szuszkiewicz, W.; Kamińska, Agnieszka; Story, T.

doi:10.1021/nl500896d

Cited by 29 publications

(20 citation statements)

References 50 publications

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“…In the case of the as grown material the coupling is effective only at the very low temperatures, as indicated in the panel (a) of Figure 5, and operates at mesoscopically short distances, as elaborated previously for similar NWs 30,31 and, generally seen in the low hole density (Ga,Mn)As. 30,40,41,42 Therefore, the magnetism of the thermally non-treated NWs assumes a heterogeneous form akin to that of nanomagnets, however, with this profound distinction that the whole Mn-rich shell is perfectly homogenous both chemically and structurally. None of the structural or element sensitive characterization tools can actually point the difference between these fragments that generate the magnetic flux and the rest of the sample.…”

Section: Magnetic Propertiessupporting

confidence: 62%

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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Section: Magnetic Propertiessupporting

confidence: 62%

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

et al. 2019

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“…31 It has to be underlined that in general the magnetic results reported here share plenty commonalities with those of the single shell (Ga,In)As/(Ga,Mn)As NWs. 20 Namely, (i) the sizable low-temperature ) resulting from the presence of quantum critical fluctuations in the local density of states which are characteristic to the proximity to the metal-insulator transition (MIT). In these volumes the local hole density (LHD) gets sufficiently enlarged to support a local ferromagnetic (FM) order due to the Zener mechanism.…”

Section: Resultsmentioning

confidence: 99%

“…In such conditions lighter (Ga,Al)As appear darker. STEM images taken along the [11][12][13][14][15][16][17][18][19][20] zone axis permit to determine clearly the interfaces between different shells along the NW length. The tomography was performed with the following parameters: electron probe size 0. paramagnetic test sample) are achieved by degaussing the magnetometer with an oscillating magnetic field of decreasing amplitude.…”

Section: Tem Imaging and Elemental Mappingmentioning

confidence: 99%

“…All these magnetic measurements are carried out by strictly observing the adequate for minute signals experimental code 46 and follow the recipes outlined in our recent study. 20 …”

Section: Tem Imaging and Elemental Mappingmentioning

confidence: 99%

“…7 These options are all well encompassed within a bottom-up approach: a controlled growth of ferromagnetic nanowires of (preferably) semiconductor origin, may serve as an ideal route to provide the necessary architecture and resulting functionalities. This is predominantly the reason of the strong ongoing interest in the elaboration of nonequilibrium growth of (Ga,Mn)As dilute ferromagnetic semiconductor (DFS) nanowires (NWs) [8][9][10][11][12][13][14][15][16][17][18][19][20][21] which would exhibit or even surpass the excellent micromagnetic properties of the prototype, epitaxial (Ga,Mn)As layers. 22 This challenge has proven to be a formidable one.…”

Section: Introductionmentioning

confidence: 99%

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Wurtzite (Ga,Mn)As nanowire shells with ferromagnetic properties

et al. 2017

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(Ga,Mn)As in wurtzite crystal structure, is coherently grown by molecular beam epitaxy on the {1100} side facets of wurtizte (Ga,In)As nanowires and further encapsulated by (Ga,Al)As and low temperature GaAs. For the first time a true long-range ferromagnetic magnetic order is observed in non-planar (Ga,Mn)As, which is attributed to a more effective hole confinement in the shell containing Mn by a proper selection/choice of both the core and outer shell materials.

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Impact of substrate temperature on magnetic properties of plasma-assisted molecular beam epitaxy grown (Ga,Mn)N

Gas

Domagała

Jakieła

et al. 2018

Journal of Alloys and Compounds

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A range of high quality Ga 1−x Mn x N layers have been grown by molecular beam epitaxy with manganese concentration 0.2  x  10%, having the x value tuned by changing the growth temperature (T g ) between 700 and 590 °C, respectively. We present a systematic structural and microstructure characterization by atomic force microscopy, secondary ion mass spectrometry, transmission electron microscopy, powder-like and high resolution X-ray diffraction, which do not reveal any crystallographic phase separation, clusters or nanocrystals, even at the lowest T g . Our synchrotron based X-ray absorption near-edge spectroscopy supported by density functional theory modelling and superconducting quantum interference device magnetometry results point to the predominantly +3 configuration of Mn in GaN and thus the ferromagnetic phase has been observed in layers with x > 5% at 3 < T < 10 K. The main detrimental effect of T g reduced to 590 o C is formation of flat hillocks, which increase the surface root-mean-square roughness, but only to mere 3.3 nm. Fine substrates' surface temperature mapping has shown that the magnitudes of both x and Curie temperature (T C ) correlate with local T g . It has been found that a typical 10 o C variation of T g across 1 inch substrate can lead to 40% dispersion of T C . The established here strong sensitivity of T C on T g turns magnetic measurements into a very efficient tool providing additional information on local T g , an indispensable piece of information for growth mastering of ternary compounds in which metal species differ in almost every aspect of their growth related parameters determining the kinetics of the growth. We also show that the precise determination of T C by two different methods, each sensitive to different moments of T C distribution, may serve as a tool for quantification of spin homogeneity within the material.

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All-Wurtzite (In,Ga)As-(Ga,Mn)As Core–Shell Nanowires Grown by Molecular Beam Epitaxy

Abstract: Structural and magnetic properties of (In,Ga)As-(Ga,Mn)As core-shell nanowires grown by molecular beam epitaxy on GaAs(111)B substrate with gold catalyst have been investigated.

Cited by 29 publications

References 50 publications

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

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

Wurtzite (Ga,Mn)As nanowire shells with ferromagnetic properties

Impact of substrate temperature on magnetic properties of plasma-assisted molecular beam epitaxy grown (Ga,Mn)N

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