Magnetic properties of InMnAs nanodots prepared by MOVPE

Novák, J.; Dujavová, Agáta; Vávra, I.; Hasenöhrl, S.; Reiffers, M.

doi:10.1016/j.jmmm.2012.09.041

Cited by 6 publications

(6 citation statements)

References 12 publications

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“…The high T C values above room temperature observed in previous works [28][29][30][31][32] is consistent with segregation of secondary phases like MnAs. This conjecture is supported by observation that whereas at low Mn concentration T C increases with concentration, the behavior typical of the DMS compounds, at high Mn concentration T C saturates [32]. We start the presentation of our results with angle-integrated photoemission (PE) spectra of shallow core levels CLs, most chemical state sensitive, for all elemental constituents of our samples.…”

Section: Xmcdsupporting

confidence: 89%

“…This vanishing FM response of our samples is actually at odds with some previous studies of similar (In,Mn)As QD systems [28][29][30][31][32]. This is however not surprising considering the small Mn concentration within the QDs in our case, on the level of a few tenths of percent, achieved with our selective doping growth process.…”

Section: Xmcdcontrasting

confidence: 82%

“…On the other hand, the strong FM response with the Curie temperature T C extending to room temperature observed in previous studies [28][29][30][31][32] could result from two effects. First, those samples could have higher degree of disorder compared to ours as evidenced by inferior quality of the TEM images [28].…”

Section: Xmcdmentioning

confidence: 75%

“…Second, the samples used in the previous studies had higher Mn concentration. Extended x-ray absorption fine structure (EXAFS) studies [29] have shown that as the Mn concentration increases the Mn-Mn interstitial pairs could form high-order dimer, trimer and cubic MnAs local atomic environments [29,32] which deliver higher FM response compared to the isolated Mn impurities. The high T C values above room temperature observed in previous works [28][29][30][31][32] is consistent with segregation of secondary phases like MnAs.…”

Section: Xmcdmentioning

confidence: 99%

“…Extended x-ray absorption fine structure (EXAFS) studies [29] have shown that as the Mn concentration increases the Mn-Mn interstitial pairs could form high-order dimer, trimer and cubic MnAs local atomic environments [29,32] which deliver higher FM response compared to the isolated Mn impurities. The high T C values above room temperature observed in previous works [28][29][30][31][32] is consistent with segregation of secondary phases like MnAs. This conjecture is supported by observation that whereas at low Mn concentration T C increases with concentration, the behavior typical of the DMS compounds, at high Mn concentration T C saturates [32].…”

Section: Xmcdmentioning

confidence: 99%

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Electronic structure of (In,Mn)As quantum dots buried in GaAs investigated by soft-x-ray ARPES

et al. 2016

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Electronic structure of a molecular beam epitaxy-grown system of (In,Mn)As quantum dots (QDs) buried in GaAs is explored with soft-x-ray angle-resolved photoelectron spectroscopy (ARPES) using photon energies around 1 keV. This technique, ideally suited for buried systems, extends the momentum-resolving capabilities of conventional ARPES with enhanced probing depth as well as elemental and chemical state specificity achieved with resonant photoexcitation. The experimental results resolve the dispersive energy bands of the GaAs substrate buried in ∼2 nm below the surface, and the impurity states (ISs) derived from the substitutional Mn atoms in the (In,Mn)As QDs and oxidized Mn atoms distributed near the surface. An energy shift of the Mn ISs in the QDs compared to (In,Mn)As DMS is attributed to the band offset and proximity effect at the interface with the surrounding GaAs. The absence of any ISs in the vicinity of the VBM relates the electron transport in (In,Mn)As QDs to the prototype (In,Mn)As diluted magnetic semiconductor. The SX-ARPES results are supported by measurements of the shallow core levels under variation of probing depth through photon energy. X-ray absorption measurements identify significant diffusion of interstitial Mn atoms out of the QDs towards the surface, and the role of magnetic circular dichroism is to block the ferromagnetic response of the (In,Mn)As QDs. Possible routes are drawn to tune the growth procedure aiming at practical applications of the (In,Mn)As based systems.

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