Colossal linear magnetoresistance in a <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si17.gif" display="inline" overflow="scroll"><mml:msub><mml:mrow><mml:mstyle mathvariant="normal"><mml:mi>CdGeAs</mml:mi></mml:mstyle></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:math>:<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si18.gif" display="inline" overflow="scroll"><mml:mstyle mathvariant="normal"><mml:mi>MnAs</mml:mi></mml:mstyle></mml:math> micro-compo

Kilański, Ł.; Dobrowolski, W.; Dynowska, E.; Wójcik, Marek J.; Kowalski, B.J.; Nedelko, N.; Ślawska‐Waniewska, A.; Maude, D. K.; Varnavskiy, S. A.; Федорченко, И. В.; Маренкин, С. Ф.

doi:10.1016/j.ssc.2011.03.036

Cited by 26 publications

(20 citation statements)

References 18 publications

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“…While the presence of these clusters would lead to spin-dependent scattering contributions to the MC, they would be unlikely to contribute to an AHE or to a measurable MOKE signal. We are aware of one other hybrid micro-composite ferromagnet -Cd 1−x Mn x GeAs 2 :MnAs -where AHE is absent despite the clear observation of ferromagnetism 23 . However, ongoing measurements of ferromagnetic resonance (FMR) in our Mn-Bi 2 Se 3 samples seem to suggest otherwise: the angular dependence of FMR shows the standard behavior seen in homogeneous ferromagnets 24 .…”

Section: Transport Measurements: Observation Of Ferromagnetism Anmentioning

confidence: 97%

Interplay between ferromagnetism, surface states, and quantum corrections in a magnetically doped topological insulator

Zhang¹,

Richardella²,

Rench³

et al. 2012

Phys. Rev. B

150

122

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The breaking of time-reversal symmetry by ferromagnetism is predicted to yield profound changes to the electronic surface states of a topological insulator. Here, we report on a concerted set of structural, magnetic, electrical and spectroscopic measurements of Mn-Bi2Se3 thin films wherein photoemission and x-ray magnetic circular dichroism studies have recently shown surface ferromagnetism in the temperature range 15 K ≤ T ≤ 100 K, accompanied by a suppressed density of surface states at the Dirac point. Secondary ion mass spectroscopy and scanning tunneling microscopy reveal an inhomogeneous distribution of Mn atoms, with a tendency to segregate towards the sample surface. Magnetometry and anisotropic magnetoresistance measurements are insensitive to the high temperature ferromagnetism seen in surface studies, revealing instead a low temperature ferromagnetic phase at T 5 K. The absence of both a magneto-optical Kerr effect and anomalous Hall effect suggests that this low temperature ferromagnetism is unlikely to be a homogeneous bulk phase but likely originates in nanoscale near-surface regions of the bulk where magnetic atoms segregate during sample growth. Although the samples are not ideal, with both bulk and surface contributions to electron transport, we measure a magnetoconductance whose behavior is qualitatively consistent with predictions that the opening of a gap in the Dirac spectrum drives quantum corrections to the conductance in topological insulators from the symplectic to the orthogonal class.

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Section: Transport Measurements: Observation Of Ferromagnetism Anmentioning

confidence: 97%

Interplay between ferromagnetism, surface states, and quantum corrections in a magnetically doped topological insulator

Zhang¹,

Richardella²,

Rench³

et al. 2012

Phys. Rev. B

150

122

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“…10 Moreover, our recent study reports a significant value of the Mn-ion-conducting hole exchange integral J pd ¼ (0.75 6 0.09) eV for Zn 0.997 Mn 0.003 GeAs 2 crystal. 11,12 It is hence evident that only at the low dilution limit of Mn in Zn 1-x Mn x GeAs 2 , one can expect to observe itinerant ferromagnetism.…”

Section: Introductionmentioning

confidence: 99%

Point defects and p-type conductivity in Zn1–xMnxGeAs2

Kilański

Rauch

Tuomisto

et al. 2014

Journal of Applied Physics

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Positron annihilation spectroscopy is used to study point defects in Zn1–xMnxGeAs2 crystals with low Mn content 0≤x≤0.042 with disordered zincblende and chalcopyrite structure. The role of negatively charged vacancies and non-open-volume defects is discussed with respect to the high p-type conductivity with carrier concentration 1019≤p≤1021cm−3 in our samples. Neutral As vacancies, together with negatively charged Zn vacancies and non-open-volume defects with concentrations around 1016−1018cm−3, are observed to increase with increasing Mn content in the alloy. The observed concentrations of defects are not sufficient to be responsible for the strong p-type conductivity of our crystals. Therefore, we suggest that other types of defects, such as extended defects, have a strong influence on the conductivity of Zn1–xMnxGeAs2 crystals.

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“…6,7 Room temperature ferromagnetism in Zn 1-x Mn x GeAs 2 and Cd 1-x Mn x GeAs 2 alloys with θ as high as 367 K for Zn 1-x Mn x GeAs 2 with 3 at.% of Mn 8 was found (via direct observation of NMR spectra characteristic of MnAs hyperfine structure) to be related to the presence of MnAs clusters. [9][10][11] The combination of the semiconductor matrix and metallic clusters called nanocomposite can be prospective from the point of view of applicable magnetotransport effects. The MnAs clusters, however, interact with the conducting carriers a) Electronic mail: kilan@ifpan.edu.pl inducing magnetoresistive effects with either negative values up to -50% for Zn 1-x Mn x GeAs 2 at T = 1.4 K (Refs.…”

Section: Introductionmentioning

confidence: 99%

“…% of Mn at T = 1.4 K (Ref. 11). However, in order to understand the complex magnetic properties of ferromagnetic semiconductor systems, it is necessary to study low paramagnetic ion alloying regime, where the aggregation of magnetic impurities does not occur.…”

Section: Introductionmentioning

confidence: 99%

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Homogeneous limit of Cd1−xMnxGeAs2 alloy: Electrical and magnetic properties

Kilański

Górska

Dynowska

et al. 2014

Journal of Applied Physics

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We present the studies of structural, electrical, and magnetic properties of bulk Cd 1-x Mn x GeAs 2 crystals with low Mn content, x, varying from 0 to 0.037. The studied samples have excellent crystallographic quality indicated by the presence of diffraction patterns never before observed experimentally for this compound. The electrical transport in our samples is dominated by thermal activation of conducting holes from the impurity states to the valence band with activation energy of about 200 meV. The defect states acting as ionic scattering centers with concentration in the range from 6 to 15×10 17 cm −3 are observed. The effective Mn content in our samples,x θ , determined from fit of the susceptibility data to the Curie-Weiss law, is very close to the average chemical content, x. It indicates that the Mn ions are distributed randomly, substituting the Cd sites in the host CdGeAs 2 lattice. We observe a negative Curie-Weiss temperature, |θ| ≤ 3.1 K, increasing as a function of x. This indicates the significance of the short-range interactions between the Mn ions.

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Colossal linear magnetoresistance in a CdGeAs2:MnAs micro-compo

Cited by 26 publications

References 18 publications

Interplay between ferromagnetism, surface states, and quantum corrections in a magnetically doped topological insulator

Interplay between ferromagnetism, surface states, and quantum corrections in a magnetically doped topological insulator

Point defects and p-type conductivity in Zn1–xMnxGeAs2

Homogeneous limit of Cd1−xMnxGeAs2 alloy: Electrical and magnetic properties

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