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We show that by annealing Ga1-xMnxAs thin films at temperatures significantly lower than in previous studies, and monitoring the resistivity during growth, an unprecedented high Curie temperature Tc and conductivity can be obtained. Tc is…

Materials Science · Physics 2009-11-07 K. W. Edmonds , K. Y. Wang , R. P. Campion , A. C. Neumann , N. R. S. Farley , B. L. Gallagher , C. T. Foxon

By using solid state reaction method we have fabricated the hole doped $La_{1-x}Sr_xFeAsO$ superconductors with Sr content up to 0.13. It is found that the sharp anomaly at about 150 K and the low temperature upturn of resistivity are…

Superconductivity · Physics 2015-05-13 Gang Mu , Lei Fang , Huan Yang , Xiyu Zhu , Peng Cheng , Hai-Hu Wen

By investigating the bulk superconducting state via dc magnetization measurements, we have discovered a common resurgence of the superconductive transition temperatures (Tcs) of the monolayer Bi2Sr2CuO6+{\delta} (Bi2201) and bilayer…

Superconductivity · Physics 2019-01-30 Liangzi Deng , Yongping Zheng , Zheng Wu , Shuyuan Huyan , Hung-Cheng Wu , Yifan Nie , Kyeongjae Cho , Ching-Wu Chu

We use a renormalized mean field theory to investigate the superconducting properties of underdoped cuprates embedded with overdoped or metallic regions that carry excess dopants. The overdoped regions are considered, within two different…

Superconductivity · Physics 2015-05-28 Lilach Goren , Ehud Altman

The Point Contact Andreev Reflection (PCAR) technique has already been used to measure the spin polarization of some of the dilute magnetic semiconductors, such as narrow-band (In,Mn)Sb, as well as wider gap (Ga,Mn)As. While in (In,Mn)Sb…

Superconductivity · Physics 2009-11-13 Raghava P. Panguluri , B. Nadgorny , T. Wojtowicz , X. Liu , J. K. Furdyna

In this chapter quantum many body theoretical methods have been used to study properties of GaAs - and InAs - based, small semiconductor compound quantum dots (QDs) containing manganese or vanadium atoms. Interest to such systems has grown…

Mesoscale and Nanoscale Physics · Physics 2012-09-25 Liudmila A. Pozhar

We present a Hamiltonian in real space which is well suited to study numerically the behavior of holes introduced in III-V semiconductors by Mn doping when the III$^{3+}$ ion is replaced by Mn$^{2+}$. We consider the actual lattice with the…

Materials Science · Physics 2007-10-03 A. Moreo , Y. Yildirim , G. Alvarez

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…

Strongly Correlated Electrons · Physics 2023-07-19 P. Tomczak , H. T. Diep , P. Jabłoński , H. Puszkarski

By doping MgB_2 superconductor with SiC nano-particles, we have successfully introduced pinning sites directly into the crystal lattice of MgB_2 grains (intra-grain pinning). It became possible due to the combination of counter-balanced Si…

Superconductivity · Physics 2009-11-07 S. X. Dou , A. V. Pan , S. Zhou , M. Ionescu , H. K. Liu , P. R. Munroe

The Curie temperature TC is investigated as a function of the hole concentration p in thin films of ferromagnetic semiconductor (Ga,Mn)As. The magnetic properties are probed by transport measurements and p is varied by the application of an…

Materials Science · Physics 2015-05-18 Y. Nishitani , D. Chiba , M. Endo , M. Sawicki , F. Matsukura , T. Dietl , H. Ohno

Electronic structure calculations are used to examine the magnetic properties of Fe$_2$P-based alloys and the mechanisms through which the Curie temperature and magnetocrystalline anisotropy can be optimized for specific applications. It is…

Materials Science · Physics 2017-10-18 I. A. Zhuravlev , V. P. Antropov , A. Vishina , M. van Schilfgaarde , K. D. Belashchenko

For already a decade the field of diluted magnetic semiconductors (DMS) is one of the hottest. In spite of the great success of material specific Density Functional Theory (DFT) to provide accurately critical Curie temperatures ($T_{C}$) in…

Disordered Systems and Neural Networks · Physics 2010-12-10 Richard Bouzerar , Georges Bouzerar

The results of the muon-spin rotation experiments on BCS superconductors NbB_2+x (x = 0.2, 0.34) are reported. Both samples, studied in the present work, exhibit rather broad transitions to the superconducting state, suggesting a…

Superconductivity · Physics 2009-11-13 R. Khasanov , A. Shengelaya , A. Maisuradze , D. Di Castro , R. Escamilla , H. Keller

The effect of nanoscale-SiC doping of MgB2 was investigated using transport and magnetic measurements. It was found that there is a clear correlation between the critical temperature Tc, the resistivity r, the residual resistivity ratio,…

Superconductivity · Physics 2009-11-10 S. X. Dou , V. Braccini , S. Soltanian , R. Klie , Y. Zhu , S. Li , X. L. Wang , D. Larbalestier

The structural and magnetic properties of Mn5Ge3Cx films prepared at elevated substrate temperatures TS are investigated. In particular, films with x >= 0.5 and TS = 680 K exhibit a strongly enhanced Curie temperature TC = 440 K compared to…

Materials Science · Physics 2009-10-31 M. Gajdzik , C. Suergers , M. Kelemen , H. v. Loehneysen

Using the improved slave-boson approach of the t-J Hamiltonian [Phys. Rev. B 64, 052501 (2001)] that we developed recently, we report the hole doping and temperature dependence of the superfluid weight. It is shown that at low hole doping…

Superconductivity · Physics 2007-05-23 Sung-Sik Lee , Sung-Ho Suck Salk

We show that, in contrast with the usual electron-phonon Migdal-Eliashberg theory, the critical temperature Tc of an isotropic s-wave nonadiabatic superconductor is strongly reduced by the presence of diluted non-magnetic impurities. Our…

Superconductivity · Physics 2009-10-31 M. Scattoni , C. Grimaldi , L. Pietronero

Designing the high performance magneto or elastocaloric effect in NiMnIn alloys with spin-lattice coupling in a deep freezing temperature range of 200 K to 255 K is challenging due to the limited lattice entropy change and large negative…

The seeking of room temperature ferromagnetic semiconductors, which take advantages of both the charge and spin degrees of freedom of electrons to realize a variety of functionalities in devices integrated with electronic, optical, and…

Materials Science · Physics 2018-07-26 Huan-Cheng Yang , Ben-Chao Gong , Kai Liu , Zhong-Yi Lu

It is well-known that magnetic moments are very harmful to superconductivity. A typical example is the element Mn whose compounds usually exhibit strong magnetism. Thus, it is very hard to achieve superconductivity in materials containing…

Superconductivity · Physics 2024-12-04 Ying-Jie Zhang , Yijie Zhu , Qing Li , Zhe-Ning Xiang , Tianheng Huang , Jian Sun , Hai-Hu Wen