Search query: Anomalous critical point behavior in dilute magnetic semiconductor

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abstract: In this paper we report successful synthesis and magnetic properties of (Ca,Na)(Zn,Mn)2Sb2 as a new ferromagnetic dilute magnetic semiconductor (DMS) In this DMS material the concentration of magnetic moments can be controlled independently from the concentration of electric charge carriers that are required for mediating magnetic interactions between these moments. This feature allows us to separately investigate the effect of carriers and of spins on the ferromagnetic properties of this new DMS alloy, and particularly of the critical ferromagnetic behavior. We use modified Arrott plot technique to establish critical exponents b, g, and d of this alloy. We find that at low Mn concentrations 10 at. it is governed by short range 3D Ising behavior, with experimental values of b, g, and d very close to theoretical 3D Ising values of 0.325, 1.24, and 4.815. However, as the Mn concentration increases, this DMS material exhibits a mixed phase behavior, with g retaining its 3D Ising characteristics, but b crossing over to longer range mean field behavior.
author_names: Shuang-jiang Yu

Xinyu Liu

Guoqiang Zhao

Yi Peng

Xiancheng Wang

Jianfa Zhao

Wenmin Li

Zheng Deng

Jacek K Furdyna

Yasutomo J Uemura

Changqing Jin
title: Anomalous critical point behavior in dilute magnetic semiconductor (Ca,Na)(Zn,Mn)2Sb2
venue: Physical Review Materials
year: 2020

abstract: We study InSb:Mn polycrystals with different values of the Mn content. In these samples, two ferromagnetic phases have been found: MnSb nanoinclusions with TC 600 K and an InMnSb magnetic host with TC below 10 K. The magnetic field dependence obtained for the measured Hall resistance exhibits a nonlinear behavior within a wide temperature range. At high temperatures, such a behavior can be attributed to the existence of two types of charge carriers, namely, light and heavy holes. At temperatures below the Curie point of the InMnSb host, the anomalous Hall effect contributing to the nonlinearity of the Hall resistance has been observed. Ferromagnetic MnSb inclusions do not contribute to the anomalous Hall effect. They do not lead to any spin polarization of charge carriers owing to the Schottky barrier, which surrounds these inclusions and prevents their interaction with charge carriers. A method has been proposed for distinguishing the anomalous Hall component in the case where the Hall resistance includes a nonlinear contribution of a different nature.
author_names: E I Yakovleva

L N Oveshnikov

Alexey V Kochura

Konstantin G Lisunov

Erkki Lahderanta

Boris A Aronzon
title: Anomalous hall effect in the In1 xMnxSb dilute magnetic semiconductor with MnSb inclusions
year: 2015

abstract: Within a Monte Carlo technique we examine critical properties of diluted bulk magnetic semiconductor (Ga,Mn)As modeled by a strongly diluted ferromagnetic Heisenberg spin \frac{5}{2} system on a face centered cubic lattice. We assumed that 5\ of Ga atoms is substituted by Mn atoms and the interaction between them is of the RKKY type. The considered system is randomly quenched and a double average was performed: firstly, over the Boltzmann probability distribution and secondly over 2048 configurations related to the quenched disorder. We estimated the critical temperature: $T_c=97\pm6$ K, which is in agreement with the experiment. The calculated high value of critical exponent \nu$ seems to point to a possibility of non universal critical behavior.
author_names: Piotr Tomczak

Hung T Diep

P Jablo'nski

Henryk Puszkarski
title: A Monte Carlo study of critical properties of strongly diluted magnetic semiconductor (Ga,Mn)As
year: 2017

abstract: Abstract We have investigated magnetic phase transitions for the dilute semiconductors Zn 1 x Mn 2+ x As 2 x =0, 0.23, 0.33) by estimating the spin spin relaxation times T 2 in the temperature range 113 360 K. From ZnMn 2 As 2 a critical anomaly in T 2 was found around T AF =175 K, consistent with anomalous behavior in magnetization observed previously. In Zn 1 x Mn 2+ x As 2 with x =0, 0.23 and 0.33, such an anomaly in T 2 was found at 225 and 235 K, respectively.
author_names: Sang Woon Ahn

Seong Gi Min

Hee-jae Kang

Suhk Kun Oh
title: Electron spin spin relaxation in dilute magnetic semiconductor Zn1 xMn2+xAs2
year: 2004

author_names: Zheng Deng

Shuang-jiang Yu

Xiancheng Wang

Yasutomo J Uemura

Changqing Jin
title: Chemical pressure effect and anomalous critical behaviors of new type of diluted magnetic semiconductors with independently charge and spin doping
year: 2020

abstract: Based on local density functional calculations, we study the exchange interactions between magnetic dopants Cr, Mn, and Fe in the III V compounds GaAs, GaN, and AlN. We show the magnetic exchange interactions deviate strongly in behavior expected from simple models, and may explain the observed maximum in critical temperature with impurity concentration. Additionally the magnetism is responsible for a strong, short range attraction between the magnetic dopants, thus creating an anomalous effective alloy hamiltonian. This suggests that the impurities may aggregate into small nanoclusters of a few magnetic atoms.
author_names: Mark van Schilfgaarde

Oleg N Mryasov
title: Anomalous exchange interactions in III V dilute magnetic semiconductors
year: 2001

abstract: Abstract The critical magnetic behavior of a weakly ferromagnetic NiRh alloy is found found to resemble the anomalous behavior recently reported for dilute Fe in Pd. From the critical coefficient values, it is shown that in NiRh ,as in PdFe, the elementary moments involved in the Curie point transition are those of giant polarization clouds rather than of individual atoms.
author_names: W C Muellner

James S Kouvel
title: Critical magnetic behavior of giant moments in NiRh
year: 1974

abstract: This focus issue of New Journal of Physics is devoted to the materials science of dilute magnetic semiconductors (DMS) A DMS is traditionally defined as a diamagnetic semiconductor doped with a few to several atomic per cent of some transition metal with unpaired d electrons. Several kinds of dopant dopant interactions can in principle couple the dopant spins leading to a ferromagnetic ground state in a dilute magnetic system. These include superexchange, which occurs principally in oxides and only between dopants with one intervening oxygen, and double exchange, in which dopants of different formal charges exchange an electron. In both of these mechanisms, the ferromagnetic alignment is not critically dependent on free carriers in the host semiconductor because exchange occurs via bonds. A third mechanism, discovered in the last few years, involves electrons associated with lattice defects that can apparently couple dopant spins. This mechanism is not well understood. Finally, the most desirable mechanism is carrier mediated exchange interaction in which the dopant spins are coupled by itinerant electrons or holes in the host semiconductor. This mechanism introduces a fundamental link between magnetic and electrical transport properties and offers the possibility of new spintronic functionalities. In particular electrical gate control of ferromagnetism and the use of spin polarized currents to carry signals for analog and digital applications. The spin light emitting diode is a prototypical device of this kind that has been extensively used to characterize the extent of spin polarization in the active light emitting semiconductor heterostructure. The prototypical carrier mediated ferromagnetic DMS is Mn doped GaAs. This and closely related narrow gap III V materials have been very extensively studied. Their properties are generally quite well understood and they have led to important insights into fundamental properties of ferromagnetic systems with strong spin orbit coupling. They have also led to the demonstration of a wide range of novel phenomena including some, like tunneling anisotropic magnetoresistance, which have subsequently been achieved in metal ferromagnetic systems. However despite considerable effort over many years the maximum Curie point achieved in (Ga,Mn)As is still less than 200 K. So unless some major new breakthrough is achieved these materials are unlikely to be of use for practical spin electronics technologies. In 2000, Dietl et al [1] published a seminal paper in which mean field theory was used to predict which of the common diamagnetic semiconductors would exhibit a Curie point above ambient if doped with 5 at. Mn and a hole concentration of 3.5 x 1020 cm 3. Of the many host semiconductors simulated, only ZnO and GaN were predicted to exhibit a critical temperature in excess of 300 K. Since 2000, high Tc DMS research has proliferated in both experimental and theoretical arenas. Many papers have been published containing claims of new DMS materials based largely on limited film growth, powder diffraction, and magnetometry. In these papers, a film which exhibits a hysteretic SQUID or VSM loop at 300 K and phase purity with only the host semiconductor detected by XRD are often claimed to be true ferromagnetic DMSs. Many of these papers are flawed because the criteria for a well defined DMS are much more extensive. These include: (i) a random dopant distribution, (ii) a well known and preferably unique charge state and preferentially a unique local structural environment for the dopant, (iii) a demonstrated coupling of the dopant spin to the host band structure, leading to spin polarization of the majority carriers, and (iv) a rational dependence of the saturation magnetization and Curie point on the magnetic dopant and carrier concentrations. Implicit in this list is that trivial causes of ferromagnetism, such as magnetic contamination and magnetic secondary phase formation, are eliminated. Yet, in many papers, the authors have not carried out the necessary control experiments and materials characterization to convincingly eliminate these possibilities. The former includes the growth of films without the magnetic dopant and the associated demonstration of the absence of ferromagnetism. Magnetic secondary phase formation is particularly problematic because in order to inject enough magnetic dopant to generate appreciable magnetization and spin polarization, one must often exceed the solid solubility of the dopant in the host. If the dopant is itself ferromagnetic in its elemental state, or if unintended magnetic products nucleate, spurious ferromagnetism will occur. Moreover, it is often a major analysis challenge to detect secondary phases when they consist of only a few per cent of the dopant; element specific spectroscopies such as x ray absorption have been invaluable in this task. Powder diffraction is not sufficiently sensitive for this level of analysis. Against this backdrop, this focus issue of New Journal of Physics now appears. The editors' principal goal in soliciting papers has been to encourage investigators to submit work in which the necessary experiments have been done to allow the material to be adequately characterized. This collection contains a mix of experimental and theoretical papers, and many different types of materials are covered. This focus issue thus constitutes a snapshot in time of a fast moving and fascinating field of materials physics. Reference [1] Dietl T, Ohno H, Matsukura F, Cibert J and Ferrand D 2000 Science 287 1019 Focus on Dilute Magnetic Semiconductors Contents The structural, optical and magnetic properties and anomalous Hall effect of InMnP:Zn epilayers Yoon Shon, Sejoon Lee, D Y Kim, T W Kang, Chong S Yoon, Eun Kyu Kim and Jeong Ju Lee Magnetic reversal under external field and current driven domain wall motion in (Ga,Mn)As: influence of extrinsic pinning K Y Wang, A C Irvine, J Wunderlich, K W Edmonds, A W Rushforth, R P Campion, C T Foxon, D A Williams and B L Gallagher Huge tunnelling anisotropic magnetoresistance in (Ga,Mn)As nanoconstrictions A D Giddings, O N Makarovsky, M N Khalid, S Yasin, K W Edmonds, R P Campion, J Wunderlich, T Jungwirth, D A Williams, B L Gallagher and C T Foxon Lithographically and electrically controlled strain effects on anisotropic magnetoresistance in (Ga,Mn)As E De Ranieri, A W Rushforth, K Vyborny, U Rana, E Ahmad, R P Campion, C T Foxon, B L Gallagher, A C Irvine, J Wunderlich and T Jungwirth Structure and magnetism of cobalt doped ZnO thin films M Ivill, S J Pearton, S Rawal, L Leu, P Sadik, R Das, A F Hebard, M Chisholm, J D Budai and D P Norton Role of charge carriers for ferromagnetism in cobalt doped rutile TiO2 T Fukumura, H Toyosaki, K Ueno, M Nakano and M Kawasaki Ab initio study of exchange constants and electronic structure in diluted magnetic group IV semiconductors Silvia Picozzi and Marjana Lezaic Phase coherent transport in (Ga,Mn)As D Neumaier, K Wagner, U Wurstbauer, M Reinwald, W Wegscheider and D Weiss Hydrogen interstitials mediated ferromagnetism in MnxGe1 x magnetic semiconductors Xin Xin Yao, Shi Shen Yan, Shu Jun Hu, Xue Ling Lin, Chong Han, Yan Xue Chen, Guo Lei Liu and Liang Mo Mei Electronic structures of magnetic semiconductors FeCr2Se4 and Fe0.5Cu0.5Cr2Se4 B I Min, Seung Su Baik, H C Choi, S K Kwon and J S Kang Investigation of pure and Co2+ doped ZnO quantum dot electronic structures using the density functional theory: choosing the right functional Ekaterina Badaeva, Yong Feng, Daniel R Gamelin and Xiaosong Li Magnetic properties of sol gel derived doped ZnO as a potential ferromagnetic semiconductor: a synchrotron based study N R S Farley, K W Edmonds, A A Freeman, G van der Laan, C R Staddon, D H Gregory and B L Gallagher Local electronic structure of Cr in the II VI diluted ferromagnetic semiconductor Zn1 xCrxTe M Kobayashi, Y Ishida, J I Hwang, G S Song, A Fujimori, C S Yang, L Lee, H J Lin, D J Huang, C T Chen, Y Takeda, K Terai, S I Fujimori, T Okane, Y Saitoh, H Yamagami, K Kobayashi, A Tanaka, H Saito and K Ando Lack of ferromagnetism in n type cobalt doped ZnO epitaxial thin films T C Kaspar, T Droubay, S M Heald, P Nachimuthu, C M Wang, V Shutthanandan, C A Johnson, D R Gamelin and S A Chambers XMCD studies on Co and Li doped ZnO magnetic semiconductors Thomas Tietze, Milan Gacic, Gisela Schutz, Gerhard Jakob, Sebastian Bruck and Eberhard Goering Ferromagnetic semiconductors and the role of disorder B W Wessels An extensive comparison of anisotropies in MBE grown (Ga,Mn)As material C Gould, S Mark, K Pappert, R G Dengel, J Wenisch, R P Campion, A W Rushforth, D Chiba, Z Li, X Liu, W Van Roy, H Ohno, J K Furdyna, B Gallagher, K Brunner, G Schmidt and L W Molenkamp Local structural, magnetic and magneto optical properties of Mn doped SiC films prepared on a 3C SiC(001) wafer Wenhong Wang, Fumiyoshi Takano, Hironori Ofuchi and Hiro Akinaga Effects of proton irradiation on the magnetic properties of GaGdN and GaCrN J K Hite, K K Allums, G T Thaler, C R Abernathy, S J Pearton, R M Frazier, R Dwivedi, R Wilkins and J M Zavada
author_names: Scott A Chambers

B L Gallagher
title: Focus on Dilute Magnetic Semiconductors
year: 2008

abstract: for an Invited Paper for the MAR05 Meeting of The American Physical Society Nanometer Scale Structure and Properties of Dilute Semiconductor Alloys RACHEL S. GOLDMAN, University of Michigan For many compound semiconductors, the addition of dilute concentrations of impurities leads to dramatic changes in the electronic, optical, and magnetic properties. For example, the introduction of a few percent nitrogen into GaAs leads to a band gap reduction of 100s of meV. Furthermore, the incorporation of a few percent manganese into GaAs enables a combination of semiconducting and ferromagnetic behavior. The resulting dilute semiconductor alloys are promising for several applications ranging from long wavelength light emitters and high efficiency solar cells to spin electronics and spin optoelectronics. In both cases, the nanometer scale details of impurity incorporation are critical to understanding and controlling the observed properties. In this talk, I will discuss our recent investigations of the growth, nanometer scale structure, and properties of dilute GaAsN and GaMnAs alloys, using nuclear reaction analysis and scanning tunneling microscopy, in conjunction with several other measurements. In GaAsN, we examine the role of surface reconstruction on the incorporation of nitrogen into substitutional vs. interstitial lattice sites, as well as the effect of nitrogen incorporation mechanisms on electronic and optical properties [1] In the case of GaMnAs, we quantify clustering of MnGa and AsGa point defects, and its effect on electronic and magnetic properties [2] [1] M. Reason, H. McKay, W. Ye, S. Hanson, V. Rotberg, and R.S. Goldman, "Mechanisms of Nitrogen Incorporation in GaAsN Alloys," Appl. Phys. Lett. 85, 1692 (2004) [2] J.N. Gleason, M. Hjelmstad, V.D. Dasika, R.S. Goldman, S. Fathpour, S. Charkrabarti, and P.K. Bhattacharya, "Nanometer scale Studies of Point Defect Distributions in GaMnAs Alloys," Appl. Phys. Lett. in press (January 3, 2005)
author_names: Michael Hjelmstad
title: Nanometer Scale Structure and Properties of Dilute Semiconductor Alloys
year: 2005

abstract: The purpose of this study was to investigate the magnetotransport properties of the Ge0.743Pb0.183Mn0.074Te mixed crystal. The results of magnetization measurements indicated that the compound is a spin glass like diluted magnetic semiconductor with critical temperature TSG 97.5 K. Nanoclusters in the sample are observed. Both, matrix and clusters are magnetically active. Resistivity as a function of temperature has a minimum at 30 K. Below the minimum a variable range hopping is observed, while above the minimum a metallic like behavior occurs. The crystal has high hole concentration, p 6.6x 10 cm 3, temperature independent. Magnetoresistance amplitude changes from 0.78 to 1.18% with increase of temperature. In the magnetotransport measurements we observed the anomalous Hall e ect with hysteresis loops. Calculated anomalous Hall e ect coe cient, RS 2.0x 10 m/C, is temperature independent. The analysis indicates the extrinsic skew scattering mechanism to be the main physical mechanism responsible for anomalous Hall e ect in Ge0.743Pb0.183Mn0.074Te alloy.
author_names: A Podgorni

L Kilanski

Witold Dobrowolski

Malgorzata Gorska

Viktor Domukhovski

B Brodowska

Anna Reszka

Bogdan J Kowalski

V E Slynko

E I Slynko
title: Anomalous Hall Effect in Ge1 x yPbxMnyTe Composite System
year: 2014