scholarly journals Epitaxial Growth of High Curie-Temperature Ge1-xMnx quantum dots on Si(001) by auto-assembly

2014 ◽  
Vol 24 (1) ◽  
pp. 69 ◽  
Author(s):  
Luong Thi Kim Phuong ◽  
An Manh Nguyen
Keyword(s):  
Quantum Dots ◽  
Curie Temperature ◽  
Epitaxial Growth ◽  
Room Temperature ◽  
Spin Injection ◽  
High Curie Temperature ◽  
Secondary Phases ◽  
Si Substrate ◽  
Mn Diffusion ◽  
Ferromagnetic Ordering

We report on successful growth of epitaxial and high Curie-temperature Ge1-xMnx quantum dots on Si (001) substrates using the auto-assembled approach. By reducing the growth temperature down to 400 °C, we show that the Mn diffusion into the Si substrate can be neglected. No indication of secondary phases or clusters was observed. Ge1-xMnx quantum dots were found to be epitaxial and perfectly coherent to the Si substrate. We also observe ferromagnetic ordering in quantum dots at a temperature higher 320 K. It is believed that single-crystalline quantum dots exhibiting a high Curie temperature are potential candidates for spin injection at temperatures higher than room temperature.

Screening and Design of Novel 2D Ferromagnetic Materials with High Curie Temperature above Room Temperature

2018 ◽  
Vol 10 (45) ◽  
pp. 39032-39039 ◽  
Author(s):  
Zhou Jiang ◽  
Peng Wang ◽  
Jianpei Xing ◽  
Xue Jiang ◽  
Jijun Zhao
Keyword(s):  
Curie Temperature ◽  
Room Temperature ◽  
Ferromagnetic Materials ◽  
High Curie Temperature

Novel Room-temperature Ferromagnetic Semiconductors Pb1-x-yCaxCryTe

2009 ◽  
Vol 1183 ◽  
Author(s):  
Evgeny P. Skipetrov ◽  
Elena A. Zvereva ◽  
Nikolay A. Pichugin ◽  
Alexey E. Primenko ◽  
Evgeny I. Slyn'ko ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Curie Temperature ◽  
Room Temperature ◽  
Diluted Magnetic Semiconductors ◽  
Magnetic Semiconductors ◽  
Impurity Level ◽  
Ferromagnetic Semiconductors ◽  
Magnetization Curves ◽  
Diluted Magnetic ◽  
Ferromagnetic Ordering

Abstract The galvanomagnetic and magnetic properties of novel diluted magnetic semiconductors Pb1-x-yCaxCryTe (x=0.06-0.20, y=0.003-0.045) have been investigated. Temperature dependencies of the resistivity and the Hall coefficient have a metallic character indicating the pinning of Fermi level by the chromium impurity level on the background of the conduction band states. Magnetization curves display a clear hysteresis loop over the whole temperature range investigated. The Curie temperature, determined from the temperature dependencies of magnetization, achieves 345 K. Possible mechanisms of ferromagnetic ordering were discussed.

scholarly journals Tunnel Contacts for Spin Injection into Silicon: The Si-Co Interface with and without a MgO Tunnel Barrier—A Study by High-Resolution Rutherford Backscattering

2012 ◽  
Vol 2012 ◽  
pp. 1-13 ◽  
Author(s):  
S. P. Dash ◽  
D. Goll ◽  
P. Kopold ◽  
H. D. Carstanjen
Keyword(s):  
High Resolution ◽  
Room Temperature ◽  
Spin Injection ◽  
Schottky Contact ◽  
Tunnel Barrier ◽  
Si Substrate ◽  
High Crystalline Quality ◽  
Tunnel Barriers ◽  
Interface Structures

In order to obtain high spin injection efficiency, a ferromagnet-semiconducor Schottky contact must be of high crystalline quality. This is particularly important in the case of ferromagnet-silicon interfaces, since these elements tend to mix and form silicides. In this study Co-Si (100) interfaces were prepared in three different ways: by evaporation at room temperature, low temperature (), and with Sb as surfactant, and their interface structures were analyzed by high-resolution RBS (HRBS). In all cases more or less strong in-diffusion of Co with subsequent silicide formation was observed. In order to prevent the mixing of Co and Si, ultra thin MgO tunnel barriers were introduced in-between them. In situ HRBS characterization confirms that the MgO films were very uniform and prevented the mixing of the Si substrate with deposited Co and Fe films effectively, even at .

High Curie temperature and carrier mobility of novel Fe, Co and Ni carbide MXenes

Nanoscale ◽  
2020 ◽  
Vol 12 (21) ◽  
pp. 11627-11637 ◽  
Author(s):  
Y. Hu ◽  
X. Y. Liu ◽  
Z. H. Shen ◽  
Z. F. Luo ◽  
Z. G. Chen ◽  
...  
Keyword(s):  
Curie Temperature ◽  
Carrier Mobility ◽  
Room Temperature ◽  
High Curie Temperature

MXenes have intrinsic and robust ferromagnetism well above room temperature as well as high and anisotropic carrier mobility.

Ferromagnetic Ordering at Room Temperature in ZnO:Co Nanoparticles

2006 ◽  
Vol 957 ◽  
Author(s):  
Sujeet Chaudhary ◽  
Kanwal Preet Bhatti ◽  
Shankhmala Kundu ◽  
Subhash C. Kashyap ◽  
Dinesh K. Pandya
Keyword(s):  
Curie Temperature ◽  
Optical Spectrum ◽  
Room Temperature ◽  
Sintering Temperature ◽  
Room Temperature Ferromagnetism ◽  
Ferromagnetic Phase ◽  
Chemical Route ◽  
Magnetic Polarons ◽  
Co Concentration ◽  
Ferromagnetic Ordering

ABSTRACTIntrinsic room temperature ferromagnetism is reported in sequentially sintered (in air ambient) nanocrystalline ZnO:Co (1 to 10 at% Co) samples prepared by chemical route. The Curie temperature of the ZnO:Co ferromagnetic samples is determined to be ∼495°C. The saturation magnetization of the ferromagnetic phase is found to first increase with Co concentration (up to 5%) and then decrease. It is also found to decrease with increase in sintering temperature up to 800°C; there after it remains unaffected till 1000°C. The d-d band transitions in the optical spectrum confirm that Co2+ substitutes Zn2+ in the ZnO lattice. A plausible explanation of the observed ferromagnetic ordering is presented in terms of Bound Magnetic Polarons model.

Room temperature λ=1.3 µm photoluminescence from InGaAs quantum dots on (001) Si substrate

2002 ◽  
Vol 36 (5) ◽  
pp. 535-538 ◽  
Author(s):  
T. M. Burbaev ◽  
I. P. Kazakov ◽  
V. A. Kurbatov ◽  
M. M. Rzaev ◽  
V. A. Tsvetkov ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Room Temperature ◽  
Si Substrate

Superparamagnetic Nanocrystalline ZnFe2O4 with a Very High Curie Temperature

2008 ◽  
Vol 8 (8) ◽  
pp. 3955-3958 ◽  
Author(s):  
Sasanka Deka ◽  
P. A. Joy
Keyword(s):  
Magnetic Properties ◽  
Curie Temperature ◽  
Temperature Variation ◽  
Nanocrystalline Materials ◽  
Zinc Ferrite ◽  
Room Temperature ◽  
Magnetic Hysteresis ◽  
High Curie Temperature ◽  
Particle Sizes ◽  
Very High

Studies on the magnetic properties of nanocrystalline ZnFe2O4 synthesized by an autocombustion method are reported. Superparamagnetic behavior is observed for the nanocrystalline materials with particle sizes of 8 nm and 17nm, with superparamagnetic blocking temperatures of 65 K and 75 K, respectively. Magnetic hysteresis with very large coercivities of 533 Oe and 325 Oe, respectively, are observed at 12 K. Studies on the temperature variation of the magnetization above room temperature indicate that the Curie temperature is as high as ∼800 K when compared to the paramagnetic nature of bulk zinc ferrite at room temperature.

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