Resistivity minima and Kondo effect in ferromagnetic GaMnAs films

He, Hongtao; Yang, Chunlei; Wk, Ge; Wang, Jiannong; Dai, Xi; Wang, Yuqi

doi:10.1063/1.2108131

Cited by 46 publications

(30 citation statements)

References 15 publications

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“…Recently, transport measurements above T = 2 K were interpreted employing weak carrier localization in three-dimensions 12 and the Kondo effect. 13 The authors predict a temperature dependence ϰ T 1/2 and ϰln͑T͒, respectively, which is not according to our observation. Considering that our data cover a much larger temperature range including temperatures well below 1 K, we want to suggest an alternative interpretation.…”

Section: Discussionmentioning

confidence: 63%

“…Assuming = 0 + ␣T 1/3 as proposed by Aronov-Altshuler, we can fit the conductivity rather well below 6 K, covering the same temperature range in which Kondo and variable-range hopping models were proposed. 13,19 The resulting values for 0 and ␣ are presented in Table I. For the case of the metallic GaMn͑5.2%͒As samples A-D ͑Fig.…”

Section: Aronov-altshuler Model Applied On Conductivity Data In the Lmentioning

confidence: 99%

“…In Figs. 5 and 6, the conductivity of GaMnAs thin films of different Mn concentrations and various annealing treatments are shown according to He et al 13 and Van Esch et al 19 The nomenclature of the samples corresponds to those of the authors and the main sample parameters are listed in Table I. Assuming = 0 + ␣T 1/3 as proposed by Aronov-Altshuler, we can fit the conductivity rather well below 6 K, covering the same temperature range in which Kondo and variable-range hopping models were proposed.…”

Section: Aronov-altshuler Model Applied On Conductivity Data In the Lmentioning

confidence: 99%

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Magnetotransport properties of strainedGa0.95Mn0.05Asepilayers close to the metal-insulator transition: Description using Aronov-Altshuler three-dimensional scaling theory

et al. 2007

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The magnitude of the anisotropic magnetoresistance ͑AMR͒ and the longitudinal resistance in compressively strained Ga 0.95 Mn 0.05 As epilayers were measured down to temperatures as low as 30 mK. Below temperatures of 3 K, the conductivity decreases ϰT 1/3 over 2 orders of magnitude in temperature. The conductivity can be well described within the framework of a three-dimensional scaling theory of Anderson's transition in the presence of spin scattering in semiconductors. It is shown that the samples are on the metallic side but very close to the metal-insulator transition. At lowest temperatures, a decrease in the AMR effect is observed, which is assigned to changes in the coupling between the remaining itinerant carriers and the local Mn 5 / 2-spin moments.

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Section: Discussionmentioning

confidence: 63%

Section: Aronov-altshuler Model Applied On Conductivity Data In the Lmentioning

confidence: 99%

Section: Aronov-altshuler Model Applied On Conductivity Data In the Lmentioning

confidence: 99%

See 1 more Smart Citation

Magnetotransport properties of strainedGa0.95Mn0.05Asepilayers close to the metal-insulator transition: Description using Aronov-Altshuler three-dimensional scaling theory

et al. 2007

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“…Resistance minima have been found in magnetic semiconductors and glasses, but these materials are either dilute or have a low ordering temperature. [22][23][24] As shown in Fig. 3(a), the low-temperature (<10 K) resistivities of our samples with 0% and 1.5% Pt remain almost constant at 12 μ cm and 21 μ cm, respectively.…”

Section: Resultsmentioning

confidence: 77%

Spin correlations and Kondo effect in a strong ferromagnet

et al. 2011

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The spin structure and electron-transport behavior of Pt-substituted MnBi thin films have been investigated. The electrical resistivity of these ferromagnetic films shows an unusual low-temperature resistance minimum or Kondo effect accompanied by positive magnetoresistance. First-principles calculations show that Mn atoms displaced to the bipyramidal interstitial sites are antiferromagnetically coupled to the Mn atoms on their regular lattice sites. We explain the observed Kondo effect and the positive magnetoresistance as the consequences of local spin correlations involving Mn atoms displaced to interstitial sites by Pt doping.

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“…On the semi-logarithmic scale, the resistivity is almost linear at low temperatures under different magnetic fields. It would be interesting for further study to investigate whether this phenomenon is the signature of the Kondo effect 22 or if it 8 should be explained in terms of quantum corrections to the conductivity in the weakly localized regime for the spin-polarized universality class in (Ga,Mn)As 23 . The specimens with x = 0.15 exhibit similar transport behavior under an applied magnetic field as that of the x = 0.2 sample.…”

mentioning

confidence: 99%

(Ca,Na)(Zn,Mn)2As2: A new spin and charge doping decoupled diluted ferromagnetic semiconductor

Zhao

Chen

Deng

et al. 2014

Journal of Applied Physics

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Here we report the successful synthesis of a spin-& charge-decoupled diluted magnetic semiconductor (Ca,Na)(Zn,Mn) 2 As 2 , crystallizing into the hexagonal CaAl 2 Si 2 structure. The compound shows a ferromagnetic transition with a Curie temperature up to 33 K with 10% Na doping, which gives rise to carrier density of n p~1 0 20 cm -3 . The new DMS is a soft magnetic material with H C <400 Oe. The anomalous Hall effect is observed below the ferromagnetic ordering temperature.With increasing Mn doping, ferromagnetic order is accompanied by an interaction between the local spin and mobile charge, giving rise to a minimum in resistivity at low temperatures and localizing the conduction electrons. The system provides an ideal platform for studying the interaction of the local spins and conduction electrons. PACS number(s): 75.50. Pp, 75.30.Kz, 76.75.+i 2 Diluted magnetic semiconductors (DMS) have received much attention due to their potential for application in the field of spintronics [1][2][3][4][5] . In typical III-V DMS systems, such as (Ga,Mn)As, (In,Mn)As and (Ga,Mn)N, substitution of divalent Mn atoms into trivalent Ga or In sites leads to severely limited chemical solubility, resulting in metastable specimens only available as epitaxial thin films. Moreover, the hetero-valence substitution, which simultaneously dopes both charge and spin, makes it difficult to individually control each quantum degree of freedom.Recently, a new type of DMS, Li(Zn,Mn)As (termed "111" following the three chemical composition ratios), was discovered by Deng et al, The "122" DMS (Ba,K)(Zn,Mn) 2 As 2 shares the tetragonal ThCr 2 Si 2 structure with the "122" iron pnictide superconductor (Ba,K)Fe 2 As 2 and the antiferromagnet BaMn 2 As 2 9 , each with a lattice mismatch of less than 2%, giving rise to the unprecedented possibility of designing various interface-based devices among DMS, superconductors and magnets. Moreover, an increase in the carrier density could enhance the Curie temperature further to 230K in this 122 system. 10The idea of decoupling spin and charge has since been extended, resulting in the discovery of two 3 additional DMS system, "111" type Li(Zn,Mn)P 11 and "1111" types (La,Ca)(Zn,Mn)SbO & (La,Ca)(Zn,Mn)AsO 12,13 Depending on the composition, "122" compounds can crystallize into the tetragonal ThCr 2 Si 2 structure, as in the case of (Ba,K)(Zn,Mn) 2 As 2 , or the hexagonal CaAl 2 Si 2 structure. Interestingly, the hexagonal compounds CaMn 2 As 2 and CaMn 2 Sb 2 are fully frustrated classical magnetic systems with a honeycomb lattice of Mn atoms, exhibiting a complex magnetic phase diagram. 14 Here we report the synthesis of bulk specimens of a new DMS (Ca,Na)(Zn,Mn) 2 As 2 with the hexagonal CaAl 2 Si 2 structure, as shown in Fig. 1(a). ExperimentalPolycrystalline samples of (Ca,Na)(Zn,Mn) 2 As 2 were synthesized via the solid-state reaction method. The synthesis of starting materials CaAs and Na 3 As was described in an earlier paper. 8These starting materials were mixed with high-purity Zn, M...

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Resistivity minima and Kondo effect in ferromagnetic GaMnAs films

Cited by 46 publications

References 15 publications

Magnetotransport properties of strainedGa0.95Mn0.05Asepilayers close to the metal-insulator transition: Description using Aronov-Altshuler three-dimensional scaling theory

Magnetotransport properties of strainedGa0.95Mn0.05Asepilayers close to the metal-insulator transition: Description using Aronov-Altshuler three-dimensional scaling theory

Spin correlations and Kondo effect in a strong ferromagnet

(Ca,Na)(Zn,Mn)2As2: A new spin and charge doping decoupled diluted ferromagnetic semiconductor

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