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We present theoretical studies of temperature dependent diamagnetic-paramagnetic transitions in thin quantum rings. Our studies show that the magnetic susceptibility of metal/semiconductor rings can exhibit multiple sign flips at…

Mesoscale and Nanoscale Physics · Physics 2021-01-04 Neal Blackman , Dentcho A. Genov

We show the possibility of long-range ferrimagnetic ordering with a saturation magnetisation of the order of 1 Bohr magneton per spin for arbitrarily low concentration of magnetic impurities in semiconductors, provided that the impurities…

Materials Science · Physics 2016-07-06 R. O. Kuzian , J. Richter , M. D. Kuz'min , R. Hayn

We report an interplay between magnetism and charge transport in the ferromagnetic semiconductor GdN, pointing to the formation of magnetic polarons centred on nitrogen vacancies. The scenario goes some way to resolving a long-standing…

Strongly Correlated Electrons · Physics 2015-06-11 Franck Natali , Ben Ruck , Joe Trodahl , Do Le Binh , Stephane Vezian , Benjamin Damilano , Yvon Cordier , Fabrice Semond , Claire Meyer

Atomically thin ferromagnetic and conducting electron systems are highly desired for spintronics, because they can be controlled with both magnetic and electric fields. We present (SrRuO3)1-(SrTiO3)5 superlattices and single-unit-cell-thick…

We investigate the magnetic and magneto-optic properties of epitaxial GaN:Gd layers as a function of the external magnetic field and temperature. An unprecedented magnetic moment is observed in this diluted magnetic semiconductor. The…

Materials Science · Physics 2009-11-10 S. Dhar , O. Brandt , M. Ramsteiner , V. F. Sapega , K. H. Ploog

We demonstrate a tunable Kondo effect realized in small quantum dots. We can switch our dot from a Kondo impurity to a non-Kondo system as the number of electrons on the dot is changed from odd to even. We show that the Kondo temperature…

Mesoscale and Nanoscale Physics · Physics 2009-10-31 Sara M. Cronenwett , Tjerk H. Oosterkamp , Leo P. Kouwenhoven

The magnetization of quantum dots is discussed in terms of a relatively simple but exactly solvable model Hamiltonian. The model predicts oscillations in spin polarization as a function of dot radius for a fixed electron density. These…

Mesoscale and Nanoscale Physics · Physics 2007-10-11 A. Bansil , D. Nissenbaum , B. Barbiellini , R. Saniz

Although InP and GaAs have very similar band-structure their magnetic properties appear to drastically differ. Critical temperatures in (In,Mn)P are much smaller than that of (Ga,Mn)As and scale linearly with Mn concentration. This is in…

Disordered Systems and Neural Networks · Physics 2016-10-12 Richard Bouzerar , Denis Machon , Patrice Melinon , Daniel May , Ute Löw , Shengqiang Zhou , Georges Bouzerar

After decades of research, the low Curie temperature of ferromagnetic semiconductors remains the key problem in the development of magnetic semiconductor spintronic technologies. Removing this roadblock might require a change of the field's…

Guided by the internal-reference rule and the known band offsets in III-V and II-VI diluted magnetic semiconductors, we discuss the feasibility of obtaining p-type conductivity, required for the carrier-induced ferromagnetism, as well as…

Materials Science · Physics 2007-05-23 J. Blinowski , P. Kacman , T. Dietl

Electronic structures, exchange interaction mechanism between magnetic ions and Curie temperature of Vanadium - doped Nitrides (AlN, GaN, and InN) are studied within KKR-LSDA-CPA. It is found that the ferromagnetic super-exchange…

Materials Science · Physics 2008-01-10 V. A. Dinh , H. Katayama-Yoshida

We calculate magnetization in magnetically doped semiconductors assuming a local exchange model of carrier-mediated ferromagnetic mechanism and using a number of complementary theoretical approaches. In general, we find that the results of…

Materials Science · Physics 2009-11-07 S. Das Sarma , E. H. Hwang , A. Kaminski

We present a detailed study, within the mean-field approximation, of an impurity band model for III-V diluted magnetic semiconductors. Such a model should be relevant at low carrier densities, below and near the metal-insulator transition.…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Mona Berciu , R. N. Bhatt

Films of ZnO doped with magnetic ions, Mn and Co and, in some cases, with Al have been fabricated with a very wide range of carrier densities. Ferromagnetic behaviour is observed in both insulating and metallic films, but not when the…

Materials Science · Physics 2009-11-13 A. J. Behan , A. Mokhtari , H. J. Blythe , D. Score , X-H. Xu , J. R. Neal , A. M. Fox , G. A. Gehring

On a basis of extensive analytical and numerical studies we show that a linear-polarized microwave field creates a stationary magnetization in mesoscopic ballistic quantum dots with two-dimensional electron gas being at a thermal…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 A. D. Chepelianskii , D. L. Shepelyansky

The current status and prospects of research on ferromagnetism in semiconductors are reviewed. The question of the origin of ferromagnetism in europium chalcogenides, chromium spinels and, particularly, in diluted magnetic semiconductors is…

Materials Science · Physics 2009-11-07 Tomasz Dietl

We analyze the heat current traversing a quantum dot sandwiched between a ferromagnetic and a superconducting electrode. The heat flow generated in response to a voltage bias presents rectification as a function of the gate potential…

Mesoscale and Nanoscale Physics · Physics 2018-04-24 Sun-Yong Hwang , David Sanchez

Ferromagnetism is an exciting phase of matter exhibiting strongly correlated electron behavior and a standard example of spontaneously broken rotational symmetry: below the Curie temperature, atomic magnets in an isotropic single-domain…

Other Condensed Matter · Physics 2018-04-06 E. Solano-Carrillo

Magnetism of $UGe_2$ is due to the magnetic ordered moments of $5f$ uranium electrons. The strong spin-orbit coupling splits them into two groups. The magnetization is investigated in terms of two vector fields ${\bf M}_{1i}$ and ${\bf…

Strongly Correlated Electrons · Physics 2015-03-17 Naoum Karchev

We report the first evidence of electron-mediated ferromagnetism in a molecular-beam-epitaxy (MBE) grown $GaAs/Al_{0.3}Ga_{0.7}As$ heterostructure with Mn $\delta$-doping. The interaction between the magnetic dopants (Mn) and the…

Mesoscale and Nanoscale Physics · Physics 2008-07-02 A. Bove , F. Altomare , N. B. Kundtz , Albert M. Chang , Y. J. Cho , X. Liu , J. Furdyna
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