A CaAl 2 Si 2 -Type Magnetic Semiconductor (Sr, Na)(Zn, Mn)2Sb2 Isostructural to 122-Type Iron-Based Superconductors

A new diluted magnetic semiconductor (Sr, Na)(Zn, Mn)2Sb2 has been successfully synthesized by doping Na and Mn into the parent compound SrZn 2 Sb 2 , which has a CaAl 2 Si 2 -type crystal structure (space group P 3 ¯ m 1 , No. 164, h P 5 ) isostructural to the 122-type iron-based superconductor CaFe 2 As 2 . No magnetic ordering has been observed when only spins are doped by (Zn, Mn) substitution. Only with carriers codoped by (Sr, Na) substitution, a ferromagnetic ordering occurs below the maximum Curie temperature T C ∼9.5 K. Comparing with other CaAl 2 Si 2 -type diluted magnetic semiconductors, we will show that negative chemical pressure suppresses the Curie temperature.

Room Temperature Intrinsic Diluted Magnetic Semiconductor Li(Cd,Mn)As

Room temperature intrinsic diluted ferromagnetic semiconductor (DMS) is highly desirable for application in spintronics. Here we report room temperature ferromagnetism in Li1.04(Cd1-xMnx)As . A Curie temperature of 318 K has...

Structural, Electronic and Magnetic Properties of GaMnN, MnN and Rare-Earth Nitride Thin Films

<p>Materials that combine the useful properties of magnetic and semiconducting behaviours are sought for new and developing applications in electronics. In this thesis experimental studies of the properties of disordered thin films of several potentially magnetic semiconducting materials are presented. Previous research on the diluted magnetic semiconductor GaMnN is reviewed as an introduction to a study of GaMnN thin films grown with an ion-assisted deposition technique. Several complementary compositional and structural analysis techniques are used to determine that films can be grown with as much as 18 at. % Mn content and that contain no impurity phases, as are often detected in single crystalline GaMnN preparations with high Mn concentrations. The effects of varying Mn contents on the resistive, optical and magnetic properties of the thin films are investigated. The structural, electronic and magnetic properties of thin films of the potential impurity phase MnN have also been investigated and compared with band structure calculations. Recent predictions that the rare earth nitrides may have extremely useful electronic properties have been almost untested in the literature. A procedure for growing rare earth nitride thin films and capping them to protect from reaction with water vapour allows their resistivity, structural and magnetic properties to be established. The results on GdN, SmN, ErN and DyN support the recent predictions, and a more thorough study on GdN reveals that this material is a ferromagnetic semiconductor below 69 K.</p>

Structural, Electronic and Magnetic Properties of GaMnN, MnN and Rare-Earth Nitride Thin Films

<p>Materials that combine the useful properties of magnetic and semiconducting behaviours are sought for new and developing applications in electronics. In this thesis experimental studies of the properties of disordered thin films of several potentially magnetic semiconducting materials are presented. Previous research on the diluted magnetic semiconductor GaMnN is reviewed as an introduction to a study of GaMnN thin films grown with an ion-assisted deposition technique. Several complementary compositional and structural analysis techniques are used to determine that films can be grown with as much as 18 at. % Mn content and that contain no impurity phases, as are often detected in single crystalline GaMnN preparations with high Mn concentrations. The effects of varying Mn contents on the resistive, optical and magnetic properties of the thin films are investigated. The structural, electronic and magnetic properties of thin films of the potential impurity phase MnN have also been investigated and compared with band structure calculations. Recent predictions that the rare earth nitrides may have extremely useful electronic properties have been almost untested in the literature. A procedure for growing rare earth nitride thin films and capping them to protect from reaction with water vapour allows their resistivity, structural and magnetic properties to be established. The results on GdN, SmN, ErN and DyN support the recent predictions, and a more thorough study on GdN reveals that this material is a ferromagnetic semiconductor below 69 K.</p>

The impact of hydrogenation conditions on the physical properties of the degenerated Ni/Al co-doped diluted magnetic semiconductor anatase nanoparticles

: Anatase (TiO2) nanoparticles co-doped with Ni/Al ions were synthesized by a thermo-precipitation method. The samples were characterized by using X‐Ray diffraction and optical absorption spectroscopy. The structural/optical investigations established the development of substitutional solid solutions: TiO2:Ni:Al. The magnetization investigations were performed to study the generated stable ferromagnetic properties of the samples due to the Ni2+ doping. To boost the created ferromagnetic properties, Al ions co-dopings were employed to supply/densify the itinerant electrons. It was planned to decide the suitable hydrogenation conditions and temperature (TH), which are necessary to create appreciable strength of ferromagnetic properties in the host co-doped samples based on TiO2 for practical uses. The results established that the ferromagnetic energy (Umag) was increased by ~240% and the saturation magnetization by ~140% with increasing of TH from 400 oC to 500oC. The obtained Msat was higher by ~50 times than that previously attained for Ni-doped TiO2. Such novel results were discussed and explained through the spin-spin Heisenberg interactions.