Dielectric and optical phonon anomalies near antiferromagnetic ordering in LaCrO3: A possible near room temperature magnetodielectric system

2013 ◽  
Vol 103 (15) ◽  
pp. 152906 ◽  
Author(s):  
Brajesh Tiwari ◽  
A. Dixit ◽  
R. Naik ◽  
G. Lawes ◽  
M. S. Ramachandra Rao
Keyword(s):  
Optical Phonon ◽  
Room Temperature ◽  
Antiferromagnetic Ordering

Photoluminescence and Magnetic Properties of Undoped and (Mn, Co) co-doped ZnO Nanoparticles

2020 ◽  
Vol 16 (4) ◽  
pp. 655-666
Author(s):  
Mona Rekaby
Keyword(s):  
Magnetic Properties ◽  
Zno Nanoparticles ◽  
Room Temperature ◽  
Magnetic Measurements ◽  
Structural Defects ◽  
Ferromagnetic Behavior ◽  
Secondary Phases ◽  
Antiferromagnetic Ordering ◽  
Doped Zno ◽  
Co Doped

Objective: The influence of Manganese (Mn2+) and Cobalt (Co2+) ions doping on the optical and magnetic properties of ZnO nanoparticles was studied. Methods: Nanoparticle samples of type ZnO, Zn0.97Mn0.03O, Zn0.96Mn0.03Co0.01O, Zn0.95Mn0.03 Co0.02O, Zn0.93Mn0.03Co0.04O, and Zn0.91Mn0.03Co0.06O were synthesized using the wet chemical coprecipitation method. Results: X-ray powder diffraction (XRD) patterns revealed that the prepared samples exhibited a single phase of hexagonal wurtzite structure without any existence of secondary phases. Transmission electron microscope (TEM) images clarified that Co doping at high concentrations has the ability to alter the morphologies of the samples from spherical shaped nanoparticles (NPS) to nanorods (NRs) shaped particles. The different vibrational modes of the prepared samples were analyzed through Fourier transform infrared (FTIR) measurements. The optical characteristics and structural defects of the samples were studied through Photoluminescence (PL) spectroscopy. PL results clarified that Mn2+ and Co2+ doping quenched the recombination of electron-hole pairs and enhanced the number of point defects relative to the undoped ZnO sample. Magnetic measurements were carried out at room temperature using a vibrating sample magnetometer (VSM). (Mn, Co) co-doped ZnO samples exhibited a ferromagnetic behavior coupled with paramagnetic and weak diamagnetic contributions. Conclusion: Mn2+ and Co2+ doping enhanced the room temperature Ferromagnetic (RTFM) behavior of ZnO. In addition, the signature for antiferromagnetic ordering between the Co ions was revealed. Moreover, a strong correlation between the magnetic and optical behavior of the (Mn, Co) co-doped ZnO was analyzed.

Polar Optical Phonon Instability and Intervalley Transfer in Gallium Nitride

1998 ◽  
Vol 512 ◽  
Author(s):  
B. E. Foutz ◽  
S. K. O'leary ◽  
M. S. Shur ◽  
L. F. Eastman ◽  
B. L. Gelmont ◽  
...  
Keyword(s):  
Gallium Nitride ◽  
Analytical Model ◽  
Optical Phonon ◽  
Room Temperature ◽  
Phonon Scattering ◽  
Polar Optical Phonon ◽  
Scattering Mechanism ◽  
Loss Mechanism ◽  
One Dimensional ◽  
Optical Phonon Scattering

ABSTRACTWe develop a simple, one-dimensional, analytical model, which describes electron transport in gallium nitride. We focus on the polar optical phonon scattering mechanism, as this is the dominant energy loss mechanism at room temperature. Equating the power gained from the field with that lost through scattering, we demonstrate that beyond a critical electric field, 114 kV/cm at T = 300 K, the power gained from the field exceeds that lost due to polar optical phonon scattering. This polar optical phonon instability leads to a dramatic increase in the electron energy, this being responsible for the onset of intervalley transitions. The predictions of our analytical model are compared with those of Monte Carlo simulations, and are found to be in satisfactory agreement.

Multiferroicity in the YFeO3 crystal

2019 ◽  
Vol 13 (01) ◽  
pp. 1950088
Author(s):  
Mingyu Shang ◽  
Haochuan Liu ◽  
Lin Zhang ◽  
Fengyue Sun ◽  
Hongming Yuan ◽  
...  
Keyword(s):  
Rare Earth ◽  
Hydrothermal Method ◽  
Room Temperature ◽  
Magnetic Measurement ◽  
Polarization Measurement ◽  
Antiferromagnetic Ordering ◽  
Saturation Polarization ◽  
Pt Electrodes ◽  
Moriya Interaction ◽  
Antiferromagnetic Behavior

In this paper, orthoferrite YFeO3 was synthesized by hydrothermal method. The space group of YFeO3 is Pnma and the spin state of [Formula: see text] ion is low spin (LS). The YFeO3 crystal exhibits a weak antiferromagnetic behavior by magnetic measurement. For the electrical polarization measurement, micron-scale Pt electrodes were deposited on the both sides of the YFeO3 crystal by FIB-induced deposition. The saturation polarization value is 0.1994[Formula: see text][Formula: see text]C/cm2 at room temperature. The crystal exhibits ferroelectric behavior through the Dzyaloshinskii–Moriya interaction induced by additional spin canting of the antiferromagnetic ordering. This work may be applied to further study of the multiferroicity in rare-earth orthoferrites RFeO3.

Room Temperature Antiferromagnetic Ordering of Nanocrystalline Tb1.90Ni0.10O3

2016 ◽  
Vol 46 (2) ◽  
pp. 1107-1113 ◽  
Author(s):  
J. Mandal ◽  
M. Dalal ◽  
B. J. Sarkar ◽  
P. K. Chakrabarti
Keyword(s):  
Room Temperature ◽  
Antiferromagnetic Ordering

Tuning the magnetic properties of graphene derivatives by functional group selection

2019 ◽  
Vol 21 (23) ◽  
pp. 12697-12703 ◽  
Author(s):  
Rostislav Langer ◽  
Piotr Błoński ◽  
Michal Otyepka
Keyword(s):  
Magnetic Properties ◽  
Functional Groups ◽  
Group Selection ◽  
Room Temperature ◽  
Functional Group ◽  
Magnetic Ordering ◽  
Functionalized Graphene ◽  
Antiferromagnetic Ordering ◽  
Graphene Derivatives

The recent discovery of hydroxofluorographene G(OH)F, a graphene derivative showing room temperature antiferromagnetic ordering, suggests that there may be other sp-materials based on sp3-functionalized graphene that exhibit magnetic ordering and whose properties can be controlled by selecting suitable functional groups.

Plasmon induced enhancement of surface optical phonon modes and magnon properties of NiO nanoparticles: Raman spectral probe

2020 ◽  
Vol 22 (39) ◽  
pp. 22815-22822 ◽  
Author(s):  
Anoop Sunny ◽  
Karthikeyan Balasubramanian
Keyword(s):  
Raman Spectroscopy ◽  
Optical Phonon ◽  
Room Temperature ◽  
Nio Nanoparticles ◽  
Phonon Modes ◽  
Surface Optical ◽  
Raman Spectral

In the present work, the influence of Ag-induced plasmons on the surface optical (SO) phonon modes of NiO nanoparticles was extensively studied using room temperature Raman spectroscopy.

scholarly journals Room temperature antiferromagnetic ordering in chemically prepared nanocrystalline Co-doped neodymium oxide (Nd1.90Co0.10O3-δ)

2018 ◽  
Vol 752 ◽  
pp. 448-454 ◽  
Author(s):  
B.J. Sarkar ◽  
M. Dalal ◽  
A. Mitra ◽  
J. Mandal ◽  
A. Bandyopadhyay ◽  
...  
Keyword(s):  
Room Temperature ◽  
Neodymium Oxide ◽  
Antiferromagnetic Ordering ◽  
Co Doped

scholarly journals Phase transition and atomic structure of Cd6Tb 1/1 approximant to quasicrystal

2014 ◽  
Vol 70 (a1) ◽  
pp. C95-C95
Author(s):  
Dan Liu ◽  
Tsunetomo Yamada ◽  
Cesar Gómez ◽  
Vaclav Petricek ◽  
Michal Dusek ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
Atomic Structure ◽  
Room Temperature ◽  
Structural Phase ◽  
Icosahedral Quasicrystal ◽  
Temperature Phase ◽  
Temperature Structure ◽  
Antiferromagnetic Ordering

We present an in-situ temperature study of the atomic structure of the 1/1 Cd6Tb approximant to an icosahedral quasicrystal. It belongs to the `Tsai' type family of quasicrystal and approximants whose archetype is the well-studied Cd-Yb system[1]. Its high temperature structure can be described as a bcc packing of a large Tsai atomic cluster, whose inner shell is a disordered tetrahedron at room temperature. As for most of the Cd6RE (RE=rare earth) approximant, the Cd6Tb phase undergoes a phase transition at 190 K to a phase of lower symmetry, resulting from an ordering of the inner tetrahedron[2]. Moreover, it has been shown that this phase undergoes a magnetic phase transition below 20 K, with an antiferromagnetic ordering of the Tb moment bearing atoms. It is thus particularly important to have a detailed structural study of this phase. We have carried out a systematic in situ measurement on a single grain from room temperature down to 40K on the crystal beam line located at the Soleil synchrotron. The structural phase transition is observed at about 190K. Using different attenuation, we have collected integrated intensity in a large dynamical range, leading to more than 60000 unique reflections in the C2/c monoclinic low temperature phase. The final wR2 values for room temperature and 40K are equal to 0.0726 and 0.0905 respectively. The resulting atomic structure will be compared to the well-studied approximant Zn6Sc, which is isostructural to Cd6Tb[3]. The ordering of the innermost tetrahedron leads to the distortion of the successive shells. The evolution of the high temperature phase, in particular just above Tc where pretransitional diffuse scattering is observed will be presented.

scholarly journals Dispersion of dielectric permittivity and magnetic properties of solid solution PZT–PFT

2015 ◽  
Vol 33 (3) ◽  
pp. 497-500 ◽  
Author(s):  
Ryszard Skulski ◽  
Przemysław Niemiec ◽  
Dariusz Bochenek ◽  
Artur Chrobak
Keyword(s):  
Phase Transition ◽  
Solid Solution ◽  
Magnetic Properties ◽  
Room Temperature ◽  
Magnetic Phase ◽  
Dielectric Dispersion ◽  
Antiferromagnetic Ordering ◽  
Mass Magnetization ◽  
Ceramic Samples ◽  
Temperature Dependences

Abstract In this paper we present the results of investigations into ceramic samples of solid solution (1-x)(PbZr0.53Ti0.47O3)- x(PbFe0.5Ta0.503) (i.e. (1-x)PZT-xPFT) with x = 0.25, 0.35 and 0.45. We try to find the relation between the character of dielectric dispersion at various temperatures and the composition of this solution. We also describe the magnetic properties of investigated samples. With increasing the content of PFT also mass magnetization and mass susceptibility increase (i.e. magnetic properties are more pronounced) at every temperature. The temperature dependences of mass magnetization and re­ciprocal of mass susceptibility have similar runs for all the compositions. However, our magnetic investigations exhibit weak antiferromagnetic ordering instead of the ferromagnetic one at room temperature. We can also say that up to room tempera­ture any magnetic phase transition has not occurred. It may be a result of the conditions of the technological process during producing our PZT-PFT ceramics.

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