| 1. |
- Gryglas-Borysiewicz, Marta, et al.
(författare)
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Hydrostatic pressure influence on T-C in (Ga,Mn)As
- 2020
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Ingår i: Physical Review B. - : American Physical Society. - 2469-9950 .- 2469-9969. ; 101:5, s. 1-10
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Tidskriftsartikel (refereegranskat)abstract
- The influence of hydrostatic pressure on the Curie temperature T-C of thin ferromagnetic (Ga,Mn)As layers is studied. New experimental data unambiguously point to both positive and negative pressure-induced changes of Curie temperature. The positive pressure coefficient is observed for samples with relatively high values of T-C and can be quantitatively described by the p-d Zener model of carrier-mediated ferromagnetism within the six-band k . p formalism and the ab initio approach. First-principles calculations of structural, electronic, and magnetic properties of (Ga,Mn)As show that antiferromagnetic coupling of substitutional Mn atoms with interstitial ones may account for a decrease of T-C under pressure in samples having a substantial concentration of interstitial Mn.
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| 2. |
- Gryglas-Borysiewicz, Marta, et al.
(författare)
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Hydrostatic-pressure-induced changes of magnetic anisotropy in (Ga, Mn) As thin films
- 2017
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Ingår i: Journal of Physics. - : Institute of Physics Publishing (IOPP). - 0953-8984 .- 1361-648X. ; 29:11
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Tidskriftsartikel (refereegranskat)abstract
- The impact of hydrostatic pressure on magnetic anisotropy energies in (Ga, Mn) As thin films with in-plane and out-of-plane magnetic easy axes predefined by epitaxial strain was investigated. In both types of sample we observed a clear increase in both in-plane and out-of-plane anisotropy parameters with pressure. The out-of-plane anisotropy constant is well reproduced by the mean-field p-d Zener model; however, the changes in uniaxial anisotropy are much larger than expected in the Mn-Mn dimer scenario.
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| 3. |
- Juszynski, Piotr, et al.
(författare)
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Study of influence of domain structure on observed magnetoresistance anomalies in GaMnAs
- 2013
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Ingår i: Applied Physics Reviews. - : AIP Publishing. - 1931-9401. ; 113:9, s. 4-093708
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Tidskriftsartikel (refereegranskat)abstract
- Magneto-transport properties of a Ga0.93Mn0.07As ferromagnetic semiconductor film with strong epitaxial strain (Ga0.7In0.3As buffer) have been studied. The observed magnetoresistance showed peculiar peaks at the magnetic fields corresponding to magnetization switching probed by Hall voltage. Computer simulations showed that these anomalies could originate from the formation of complex, island-like magnetic domains, and their propagation in the sample.
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| 4. |
- Kwiatkowski, Adam, et al.
(författare)
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Determining Curie temperature of (Ga,Mn)As samples based on electrical transport measurements: Low Curie temperature case.
- 2016
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 108:24, s. 1-4
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we show that the widely accepted method of the determination of Curie temperature (Tc) in (Ga,Mn)As samples, based on the position of the peak in the temperature derivative of the resistivity, completely fails in the case of non-metallic and low-TC unannealed samples. In this case, we propose an alternative method, also based on electric transport measurements, which exploits temperature dependence of the second derivative of the resistivity upon magnetic field.
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| 5. |
- Kwiatkowski, Adam, et al.
(författare)
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Galvanomagnetic methods of Curie temperature determination in (Ga,Mn)As
- 2018
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Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier. - 0304-8853 .- 1873-4766. ; 467, s. 120-128
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Tidskriftsartikel (refereegranskat)abstract
- We critically discuss various experimental methods to determine Curie temperature T-C of (Ga,Mn)As thin layers or other conducing magnetic materials by means of electric charge transport measurements. They all base on the influence of sample magnetization on the magnetoresistivity tensor <(rho)overcap>and are an alternative to the method based upon an analysis of the temperature derivative of the sample resistance (Novak a al., 2008). These methods can be applied even when standard SQUID magnetometers are difficult or impossible to use - for example for extremely small samples or in the case of experiments performed at very specific physical conditions, e.g. at high hydrostatic pressure inside the clamp cell. We show that the use of the so called Arrott plot prepared with the use of high magnetic field isotherms rho(xx)(H-0), rho(x)y(H-0) (H-0 - external magnetic field) may lead to substantial (of the order of 10 K) divergence of the obtained T-c values depending on the assumptions which are necessary to make in this case and depending on the direction of a magnetic anisotropy easy axis. We also propose a number of ways how to obtain, basing on low magnetic field isotherms rho(xx)(H-0), rho(xy)(H-0) clear and characteristic features which are closely related to the ferromagnetic-paramagnetic phase transition.
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