scholarly journals Degradation of the remanent ferromagnetic state under the action of ferroelectric relaxation processes in Co/(1−x)PMN-xPT/Co hybrids: Possible implications on cryogenic and room-temperature applications

2014 ◽  
Vol 116 (8) ◽  
pp. 084304 ◽  
Author(s):  
D. Stamopoulos ◽  
M. Zeibekis ◽  
G. Vertsioti ◽  
S. J. Zhang
Keyword(s):  
Room Temperature ◽  
Ferromagnetic State ◽  
Relaxation Processes ◽  
Temperature Applications

Structural and electrical properties of KCa2Nb5O15 ceramics

Open Physics ◽  
2008 ◽  
Vol 6 (2) ◽  
Author(s):  
Banarji Behera ◽  
Pratibindhya Nayak ◽  
Ram Choudhary
Keyword(s):  
Electrical Properties ◽  
Temperature Variation ◽  
Electrical Transport ◽  
Room Temperature ◽  
Complex Impedance ◽  
Tungsten Bronze ◽  
Transport Processes ◽  
Relaxation Processes ◽  
Orthorhombic Crystal Structure ◽  
Grain Distribution

AbstractA polycrystalline sample of KCa2Nb5O15 with tungsten bronze structure was prepared by a mixed oxide method at high temperature. A preliminary structural analysis of the compound showed an orthorhombic crystal structure at room temperature. Surface morphology of the compound shows a uniform grain distribution throughout the surface of the sample. Studies of temperature variation on dielectric response at various frequencies show that the compound has a transition temperature well above the room temperature (i.e., 105°C), which was confirmed by the polarization measurement. Electrical properties of the material have been studied using a complex impedance spectroscopy (CIS) technique in a wide temperature (31–500°C) and frequency (102–106 Hz) range that showed only bulk contribution and non-Debye type relaxation processes in the material. The activation energy of the compound (calculated from both the loss and modulus spectrum) is same, and hence the relaxation process may be attributed to the same type of charge carriers. A possible ‘hopping’ mechanism for electrical transport processes in the system is evident from the modulus analysis. A plot of dc conductivity (bulk) with temperature variation demonstrates that the compound exhibits Arrhenius type of electrical conductivity.

scholarly journals Ferromagnetic state above room temperature in a proximitized topological Dirac semimetal

2019 ◽  
Vol 100 (24) ◽  
Author(s):  
Masaki Uchida ◽  
Takashi Koretsune ◽  
Shin Sato ◽  
Markus Kriener ◽  
Yusuke Nakazawa ◽  
...  
Keyword(s):  
Room Temperature ◽  
Ferromagnetic State ◽  
Dirac Semimetal

Synthesis and Magnetic Properties of CoAl2O4 Coated Co Solid Solution Nanocapsules

2010 ◽  
Vol 663-665 ◽  
pp. 1256-1259
Author(s):  
Gui Mei Shi ◽  
Ge Song ◽  
Shu Lian ◽  
Jin Bing Zhang
Keyword(s):  
Solid Solution ◽  
Photoelectron Spectrum ◽  
Room Temperature ◽  
Ferromagnetic State ◽  
Antiferromagnetic Order ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Core ◽  
New Type ◽  
The Magnetic Field

A new type of antiferromagnetic CoAl2O4 coated ferromagnetic Co solid solution is synthesized by arc-discharging. Typical HRTEM images show that the nanocapsules form in a core-shell structure. The size of the nanocapsules is in range of 10-90 nm and the thickness of the shell is about 3-10 nm. X-ray photoelectron spectrum (XPS) and X-ray diffraction (XRD) reveal that the core consists of Co solid solution, while the shell is CoAl2O4. The magnetic field and temperature dependence of magnetizations confirm that the Co solid solution nanocapsules are basically in the ferromagnetic state below Curie temperature. In addition, the antiferromagnetic order occurs with Neél temperature TN of about 5 K. The saturation magnetization of Ms = 76.1 Am2/kg and the coercive force of Hc= 23.28 kA/m are achieved at room temperature for the Co solid solution nanocapsules.

scholarly journals Tuning ferromagnetism at room temperature by visible light

2020 ◽  
Vol 117 (12) ◽  
pp. 6417-6423 ◽  
Author(s):  
Bálint Náfrádi ◽  
Péter Szirmai ◽  
Massimo Spina ◽  
Andrea Pisoni ◽  
Xavier Mettan ◽  
...  
Keyword(s):  
Room Temperature ◽  
Magnetic Moments ◽  
Ferromagnetic State ◽  
Perovskite Oxide ◽  
External Control ◽  
Digital Information ◽  
Alternative Approach ◽  
Ferromagnetic Domains ◽  
Radical Method ◽  
Oxide Perovskite

Most digital information today is encoded in the magnetization of ferromagnetic domains. The demand for ever-increasing storage space fuels continuous research for energy-efficient manipulation of magnetism at smaller and smaller length scales. Writing a bit is usually achieved by rotating the magnetization of domains of the magnetic medium, which relies on effective magnetic fields. An alternative approach is to change the magnetic state directly by acting on the interaction between magnetic moments. Correlated oxides are ideal materials for this because the effects of a small external control parameter are amplified by the electronic correlations. Here, we present a radical method for reversible, light-induced tuning of ferromagnetism at room temperature using a halide perovskite/oxide perovskite heterostructure. We demonstrate that photoinduced charge carriers from theCH3NH3PbI3photovoltaic perovskite efficiently dope the thinLa0.7Sr0.3MnO3film and decrease the magnetization of the ferromagnetic state, allowing rapid rewriting of the magnetic bit. This manipulation could be accomplished at room temperature; hence this opens avenues for magnetooptical memory devices.

Synthesis, characterization of LCMO composite and fabrication of its thin films by R.F magnetron sputtering for room-temperature applications

2020 ◽  
Author(s):  
Navjyoti Boora ◽  
Poonam Rani ◽  
Vandana Nagal ◽  
Shafaque Rahman ◽  
V. P. S Awana ◽  
...  
Keyword(s):  
Thin Films ◽  
Magnetron Sputtering ◽  
Room Temperature ◽  
Temperature Applications

Thermoelectric Properties of Er-doped InGaN Alloys for High Temperature Applications

2011 ◽  
Vol 1325 ◽  
Author(s):  
K. Aryal ◽  
I. W. Feng ◽  
B. N. Pantha ◽  
J. Li ◽  
J. Y. Lin ◽  
...  
Keyword(s):  
High Temperature ◽  
Room Temperature ◽  
Chemical Vapor ◽  
Organic Chemical ◽  
Metal Organic ◽  
Er Doped ◽  
Organic Chemical Vapor Deposition ◽  
Co Doped ◽  
Ingan Alloys ◽  
Temperature Applications

ABSTRACTThermoelectric (TE) properties of erbium-silicon co-doped InxGa1-xN alloys (InxGa1-xN: Er + Si, 0≤x≤0.14), grown by metal organic chemical vapor deposition, have been investigated. It was found that doping of InGaN alloys with Er atoms of concentration, N[Er] larger than 5x1019 cm-3, has substantially reduced the thermal conductivity, κ, in low In content InGaN alloys. It was observed that κ decreases as N[Er] increases in Si co-doped In0.10Ga0.90N alloys. A room temperature ZT value of ~0.05 was obtained in In0.14Ga0.86N: Er + Si, which is much higher than that obtained in un-doped InGaN with similar In content. Since low In content InGaN is stable at high temperatures, these Er+Si co-doped InGaN alloys could be promising TE materials for high temperature applications.

scholarly journals Magnetic resonance study of co-modified (Co,N)-TiO2 nanocomposites

Nukleonika ◽  
2015 ◽  
Vol 60 (3) ◽  
pp. 411-416 ◽  
Author(s):  
Niko Guskos ◽  
Grzegorz Zolnierkiewicz ◽  
Aleksander Guskos ◽  
Janusz Typek ◽  
Pawel Berczynski ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Spin System ◽  
Concentration Index ◽  
Room Temperature ◽  
Magnetic System ◽  
Resonance Spectroscopy ◽  
Relaxation Processes ◽  
Strongly Correlated ◽  
Magnetic Resonance Study ◽  
Cobalt Ions

Abstract Three nCo,N-TiO2 nanocomposites (where cobalt concentration index n = 1, 5 and 10 wt %) were prepared and investigated by magnetic resonance spectroscopy at room temperature. Ferromagnetic resonance (FMR) lines of magnetic cobalt agglomerated nanoparticle were dominant in all registered spectra. The relaxation processes and magnetic anisotropy of the investigated spin system essentially depended on the concentration of cobalt ions. It is suggested that the samples contained two magnetic types of sublattices forming a strongly correlated spin system. It is suggested that the existence of strongly correlated magnetic system has an essential influence of the photocatalytic properties of the studied nanocomposites.

Release of Tetrahydrofuran, Structural Phase Transitions and Dynamic Relaxation Processes in Ca (BH4)2

2012 ◽  
Vol 184 ◽  
pp. 24-32 ◽  
Author(s):  
Annalisa Paolone ◽  
O. Palumbo ◽  
P. Rispoli ◽  
Rosario Cantelli ◽  
E. Rönnebro ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Room Temperature ◽  
Structural Phase ◽  
Young Modulus ◽  
Relaxation Processes ◽  
Structural Phase Transitions ◽  
Exponential Factor ◽  
Β Phase ◽  
Α Phase ◽  
Calcium Borohydride

Various calcium borohydride samples were investigated by means of combined measurements of thermogravimetry and mass spectrometry, and anelastic spectroscopy. On heating, the release of 2-5% tetrahydrofuran (THF) is detected in all the samples at temperatures below ~480 K, even in those which were previously thermally treated, according to procedures known from the literature, in order to remove the solvent. Dehydrogenation takes place above 480 K. Above room temperature the temperature dependence of the Young modulus of Ca (BH4)2clearly monitors the release of THF and two irreversible structural phase transitions: from the α to the α’ phase around 460 K and from the α’ to the β phase, nearly completely evolved around 590 K. Moreover, the coefficient of elastic energy dissipation presents two dynamic processes below room temperature; a peak around 120 K characterized by an activation energy of 0.20 eV and a pre-exponential factor typical of atom-cluster relaxations, that we attributed to the dynamics of THF molecules retained in the borohydride lattice, and a peak around 200 K, possibly due to the relaxation of H vacancies.

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