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Karczewski, G.; Sawicki, M.; Ivanov, V. Yu.; Ruester, C.; Grabecki, G.; Matsukura, F.; Molenkamp, Laurens W.; Dietl, T.

doi:10.1023/a:1023224432107

Cited by 32 publications

(8 citation statements)

References 8 publications

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“…In contrast to conventional Mn based II-VI DMSs, the Cr based DMSs such as Zn 1-x Cr x Te and Zn 1-x Cr x Se are theoretically predicted to be ferromagnetic even without carriers [1,2]. In accordance with the predictions, several groups recently reported the ferromagnetic transition of the MBE-grown (II,Cr)-VI alloys [3][4][5]. Saito et al reported the ferromagnetic transition of Zn 1-x Cr x Te at around 15 K for x = 0.035 [3].…”

Section: Introductionmentioning

confidence: 72%

“…On the other hand, Karczewski et al reported the ferromagnetism of MBE-grown Zn 1-x Cr x Se films whose Cr concentrations were 1.4% and 2%. In the report, the ferromagnetic coupling between Cr ions appeared in Zn 1-x Cr x Se films, and the authors argued the presence of clustering such as small grains of spinels containing Cr since superparamagnetic behaviours were appeared in detailed magnetization measurements of the films [5]. Thus, the origin of the ferromagnetism in these systems is now still under discussion.…”

Section: Introductionmentioning

confidence: 99%

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Magnetic properties of MBE‐grown Zn _{1−
x} Cr _x Te

Ozaki

Nishizawa

Nam

et al. 2004

phys. stat. sol. (c)

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We have grown Zn 1-x Cr x Te films by molecular-beam-epitaxy (MBE) and investigated their magnetic properties with variation of Cr concentrations (x) between 0.01-0.08. Systematic increase of the lattice constant was observed by XRD only up to around x = 0.02. Measurements of the magnetizations M-H reveal that ferromagnetic transition occurs in the films at low temperatures. The transition temperature (T C ) which was estimated from Arrott-plots increased with Cr concentration up to about 100 K for x = 0.08. However, the temperature dependence of the magnetization M-T shows different curves below T C for field-cooled (FC) and zero-field-cooled (ZFC) processes. Moreover, their paramagnetic Curie temperatures (Θ), estimated from the higher temperature M-T curves, are different from and much higher than T C . These behaviours could be attributed to the superparamagnetism in the films. Indeed, many defects such as stacking faults are observed in the sample with x = 0.08 through HRTEM. It could give rise to the distribution of the Cr concentrations and/or the presence of precipitates including Cr.

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Section: Introductionmentioning

confidence: 72%

Section: Introductionmentioning

confidence: 99%

Magnetic properties of MBE‐grown Zn _{1−
x} Cr _x Te

Ozaki

Nishizawa

Nam

et al. 2004

phys. stat. sol. (c)

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“…In addition, the intrinsic nature of ferromagnetism appeared to be confirmed by the similar magnetic-field dependences of magnetization and MCD (Saito et al, 2003). However, according to Karczewski et al, 2003, the ferromagnetism in Zn 1−x Cr x Se resulted from the precipitation of a FM compound, as T C was independent of x.…”

Section: A Introductionmentioning

confidence: 84%

“…Furthermore, nanodecomposition and, thus, other associated properties are strongly affected by changing the concentrations of donors or acceptors, either by manipulating with stoichiometry via altering the intensities of the molecular beams or by codoping with I or N, respectively. Pioneering work drawing attention to the possibility of spinodal nanodecomposition in (Zn,Cr)Se (Karczewski et al, 2003) is also discussed.…”

Section: Contentsmentioning

confidence: 99%

Spinodal nanodecomposition in semiconductors doped with transition metals

et al. 2015

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This review presents the recent progress in computational materials design, experimental realization, and control methods of spinodal nanodecomposition under three-and two-dimensional crystal-growth conditions in spintronic materials, such as magnetically doped semiconductors. The computational description of nanodecomposition, performed by combining first-principles calculations with kinetic Monte Carlo simulations, is discussed together with extensive electron microscopy, synchrotron radiation, scanning probe, and ion beam methods that have been employed to visualize binodal and spinodal nanodecomposition (chemical phase separation) as well as nanoprecipitation (crystallographic phase separation) in a range of semiconductor compounds with a concentration of transition metal (TM) impurities beyond the solubility limit. The role of growth conditions, codoping by shallow impurities, kinetic barriers, and surface reactions in controlling the aggregation of magnetic cations is highlighted. According to theoretical simulations and experimental results the TM-rich regions appear in the form of either nanodots (the dairiseki phase) or nanocolumns (the konbu phase) buried in the host semiconductor. Particular attention is paid to Mn-doped group III arsenides and antimonides, TM-doped group III nitrides, Mn-and Fe-doped Ge, and Cr-doped group II chalcogenides, in which ferromagnetic features persisting up to above room temperature correlate with the presence of nanodecomposition and account for the application-relevant magnetooptical and magnetotransport properties of these compounds. Finally, it is pointed out that spinodal nanodecomposition can be viewed as a new class of bottom-up approach to nanofabrication.

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“…The case of ZnCrSe alloy layers is of special interest due to a proposed ferromagnetic p-d exchange coupling, which is unique in DMS [26,27]. First indications of ferromagnetism in ZnCrSe layers grown by MBE were reported recently [28]. We have grown high quality, pseudomorphically strained ZnCrSe layers by MBE on (001)GaAs and characterized them in-situ by RIX as well as ex-situ by HR-XRD, secondary ion mass spectroscopy (SIMS), and superconducting quantum interference device magnetometry (SQUID).…”

Section: Epitaxial Growth and Degradation Of Zncrse Alloy Layersmentioning

confidence: 99%

In‐situ X‐ray diffraction during epitaxial growth of ZnSe‐based heterostructures on (001)GaAs

Benkert

Schumacher

Neder

et al. 2007

Phys. Status Solidi (c)

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We developed a real-time in-situ X-ray (RIX) diffraction technique for the detailed layer characterisation during epitaxial deposition of ZnSe-based alloys on (001)GaAs substrates. A conventional molecular beam epitaxy chamber was equipped with a Cu X-ray tube. The 113 reflection of the deposited structure is detected in static geometry by a CCD and is immediately analyzed in terms of strain, composition, thickness and strain relaxation behavior of the deposited layer. The in-situ monitoring of ZnCdSe layers reveals a delay of heteroepitaxial growth start on GaAs, a gradual layer degradation due to dislocation formation, and a critical thickness for plastic relaxation which depends on the Cd content, consistent with an energy-balance model. ZnCrSe alloy layers can be deposited with Cr content up to 2% at low substrate temperature T S = 210 °C. The layers appear to be epitaxial alloys with good quality, but a broadening of the Bragg peaks without a significant plastic relaxation is observed. Epitaxial growth and layer properties are studied as function of deposition conditions.

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Untitled

Cited by 32 publications

References 8 publications

Magnetic properties of MBE‐grown Zn _{1−
x} Cr _x Te

Magnetic properties of MBE‐grown Zn _{1−
x} Cr _x Te

Spinodal nanodecomposition in semiconductors doped with transition metals

In‐situ X‐ray diffraction during epitaxial growth of ZnSe‐based heterostructures on (001)GaAs

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Untitled

Cited by 32 publications

References 8 publications

Magnetic properties of MBE‐grown Zn 1− x Cr x Te

Magnetic properties of MBE‐grown Zn 1− x Cr x Te

Spinodal nanodecomposition in semiconductors doped with transition metals

In‐situ X‐ray diffraction during epitaxial growth of ZnSe‐based heterostructures on (001)GaAs

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Product

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About

Magnetic properties of MBE‐grown Zn _{1−
x} Cr _x Te

Magnetic properties of MBE‐grown Zn _{1−
x} Cr _x Te