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Copper and Nickel impurities have been doped into the iron pnictide superconductor Ba0.6K0.4Fe2As2. Resistivity measurements reveal that Cu and Ni impurities suppress superconducting transition temperature T_c with rates of \Delta T_c/Cu-1%…

Superconductivity · Physics 2015-06-15 Peng Cheng , Bing Shen , Fei Han , Hai-Hu Wen

We report electrical resistivity, magnetic and magnetocaloric properties in Sm0.7-xLaxSr0.3MnO3 series for x= 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.65, and 0.7. All the compounds show second order paramagnetic to ferromagnetic transition at T…

Materials Science · Physics 2015-06-11 M. Aparnadevi , R. Mahendiran

We present the investigation results of the in-plane \{rho}(T) resistivity tensor at the temperature range 0.4-40 K in magnetic fields up to 90kOe (H||c, J||ab) for electron-doped Nd{2-x}Ce{x}CuO{4+{\delta}} with different degree of…

Ferromagnetic couplings in spin clusters are shown to be strongly enhanced compared to those for an ordered impurity arrangement, even for the same spin separation and hole doping. The consequent energy-enhancement of the cluster-localized…

Strongly Correlated Electrons · Physics 2007-05-23 Avinash Singh

Using spin-1/2 description of valence holes and Kondo coupling between local spins and carriers, GaAs-based III-V diluted magnetic semiconductors (DMS)are studied in the coherent potential approximation(CPA). Our calculated relation of…

Materials Science · Physics 2009-11-11 Sze-Shiang Feng , Mogus Mochena

We study theoretically the effect of the fermion and boson densities on the superconductivity transition critical temperature $(T_c)$ of a two dimensional electron gas (2DEG), where superconductivity is mediated by a Bose-Einstein…

Superconductivity · Physics 2014-10-15 E. D. Cherotchenko , T. Espinosa-Ortega , A. V. Nalitov , I. A. Shelykh , A. V. Kavokin

We report an unexpected positive hydrostatic pressure derivative of the superconducting transition temperature in the doped topological insulator \NBS via $dc$ SQUID magnetometry in pressures up to 0.6 GPa. This result is contrary to…

Superconductivity · Physics 2017-11-01 M. P. Smylie , K. Willa , K. Ryan , H. Claus , W. -K. Kwok , Y. Qiu , Y. S. Hor , U. Welp

Electronic Raman scattering from high- and low-energy excitations was studied as a function of temperature, extent of hole doping, and energy of the incident photons in Bi_2Sr_2CaCu_2O_{8 \pm \delta} superconductors. For underdoped…

Superconductivity · Physics 2009-10-30 G. Blumberg , M. Kang , M. V. Klein , K. Kadowaki , C. Kendziora

The upper critical field, $H_{c2}$, of Mg(B$_{1-x}$C$_x$)$_2$ has been measured in order to probe the maximum magnetic field range for superconductivity that can be attained by C doping. Carbon doped boron filaments are prepared by CVD…

The magnetic properties of the Zn-substituted overdoped high-$T_c$ superconductor La$_{2-x}$Sr$_{x}$Cu$_{1-y}$Zn$_{y}$O$_{4}$ have been studied by magnetization measurements and neutron scattering. Magnetization measurements reveal that for…

Superconductivity · Physics 2009-11-11 S. Wakimoto , R. J. Birgeneau , A. Kagedan , Hyunkyung Kim , I. Swainson , K. Yamada , H. Zhang

A range of high quality Ga1-xMnxN layers have been grown by molecular beam epitaxy with manganese concentration 0.2 < x < 10%, having the x value tuned by changing the growth temperature (Tg) between 700 and 590 {\deg}C, respectively. We…

We examine the feasibility of a simple description of Mn ions in III-V diluted magnetic semiconductors (DMSs) in terms of two species (components), motivated by the expectation that the Mn-hole exchange couplings are widely distributed,…

Disordered Systems and Neural Networks · Physics 2009-11-07 Malcolm P. Kennett , Mona Berciu , R. N. Bhatt

We propose a theory which allow to calculate the magnetic excitation spectrum in diluted ferromagnetic systems. The approach is rather general and based on the Self-Consistent local Random Phase Approximation in which disorder (dilution)…

Disordered Systems and Neural Networks · Physics 2009-11-11 Georges Bouzerar

We report on study of magnetic impurities spin relaxation in diluted magnetic semiconductors above Curie temperature. Systems with a high concentration of magnetic impurities where magnetic correlations take place were studied. The…

Materials Science · Physics 2021-08-27 I. V. Krainov , V. F. Sapega , G. S. Dimitriev , N. S. Averkiev

We present a theoretical survey of ferromagnetic transition temperatures in cubic (III,Mn)V semiconductors based on a model with $S=5/2$ local moments exchange-coupled to itinerant holes in the host semiconductor valence band. Starting from…

Materials Science · Physics 2016-08-16 T. Jungwirth , Jürgen König , Jairo Sinova , J. Kučera , A. H. MacDonald

Molecular beam epitaxy has been employed to obtain Ga1-xMnxN films with x up to 10% and Curie temperatures T_C up to 13 K. The magnitudes of T_C and their dependence on x, T_C(x) ~ x^m, where m = 2.2 +/- 0.2 are quantitatively described by…

Disordered Systems and Neural Networks · Physics 2013-11-15 S. Stefanowicz , G. Kunert , C. Simserides , J. A. Majewski , W. Stefanowicz , C. Kruse , S. Figge , Tian Li , R. Jakiela , K. N. Trohidou , A. Bonanni , D. Hommel , M. Sawicki , T. Dietl

Growth of GaMnAs by molecular beam epitaxy is typically performed at low substrate temperatures (250C) and high As overpressures leading to the incorporation of excess As and Mn interstitials, which quench optical signals such as…

Materials Science · Physics 2009-09-29 M. Poggio , R. C. Myers , N. P. Stern , A. C. Gossard , D. D. Awschalom

We present the first study of codoped iron-arsenide superconductors of the 122 family (Sr/Ba)_(1-x)K_xFe_(2-y)Co_yAs_2 with the purpose to increase the upper critical field H_c2 compared to single doped (Sr/Ba)Fe_2As_2 materials. H_c2 was…

Superconductivity · Physics 2017-09-27 F. Weickert , M. Nicklas , W. Schnelle , J. Wosnitza , A. Leithe-Jasper , H. Rosner

Cross-control of a material property - manipulation of a physical quantity (e.g., magnetisation) by a nonconjugate field (e.g., electrical field) - is a challenge in fundamental science and also important for technological device…

Materials Science · Physics 2016-05-19 M. Kriener , T. Nakajima , Y. Kaneko , A. Kikkawa , X. Z. Yu , N. Endo , K. Kato , M. Takata , T. Arima , Y. Tokura , Y. Taguchi

Nominally 45 nm GaN:Mg/ 5 nm (Ga,Mn)N / 45 nm GaN:Mg trilayers structures prepared by molecular beam epitaxy on GaN-buffered Al2O3 substrates are investigated to verify whether the indirect co-doping by holes from the cladding layers can…

Materials Science · Physics 2021-02-25 Katarzyna Gas , Gerd Kunert , Piotr Dluzewski , Rafal Jakiela , Detlef Hommel , Maciej Sawicki