scholarly journals High-field Study of Layered Manganites R1/2Sr3/2MnO4 (R = La and Nd)

1999 ◽  
Vol 52 (2) ◽  
pp. 227
Author(s):  
M. Tokunaga ◽  
N. Miura ◽  
Y. Moritomo
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Field Study ◽  
Transport Properties ◽  
Low Temperatures ◽  
High Field ◽  
Colossal Magnetoresistance ◽  
Real Space ◽  
Charge Ordering ◽  
Pulsed Magnetic Fields

We have studied the effects of a magnetic field on the magnetism and transport properties of the layered manganites R1/2Sr3/2MnO4 (R = La and Nd) in pulsed magnetic fields up to 40 T. The R = La crystal shows metamagnetic-like transitions above 30 T, concomitantly with a colossal magnetoresistance (CMR) effect as large as [ρ(0) - ρ(H)]/ρ(H) > 103 with a field of µοH = 38 T at low temperatures. These transitions can be ascribed to the field-induced melting of the real-space ordering of the eg electrons (charge ordering). For the R = Nd crystal, a magnetic field along the c-axis enhances the two-dimensionality in the conductivity. Moreover, we observed metamagnetic-like transitions accompanied by the CMR effects at low temperatures, in spite of the absence of charge ordering.

HIGH-FIELD TRANSPORT PROPERTIES OF T'-Ln2-xCexCuO4 (Ln=Nd, Pr, La)

2002 ◽  
Vol 16 (20n22) ◽  
pp. 3216-3219 ◽  
Author(s):  
T. SEKITANI ◽  
N. MIURA ◽  
M. NAITO
Keyword(s):  
Magnetic Field ◽  
Low Temperature ◽  
Magnetic Fields ◽  
Transport Properties ◽  
Normal State ◽  
Low Temperatures ◽  
High Field ◽  
Magnetic Moments ◽  
Negative Magnetoresistance ◽  
High Magnetic Fields

We report low-temperature magnetotransport in the normal state of the electron-doped superconductors, Nd 2-x Ce x CuO 4, Pr 2-x Ce x CuO 4, and La 2-x Ce x CuO 4, by suppressing the superconductivity with high magnetic fields. The normal state ρ-T curve shows an up-turn at low temperatures, which has a log T dependence with saturation at lowest temperatures. The up-turn is gradually suppressed with increasing magnetic field, resulting in negative magnetoresistance. We discuss these findings on the basis of the Kondo scattering originating from the magnetic moments of Cu 2+ ions.

scholarly journals Martensitic transformation in the systems based on Fe-Ni compositions in strong pulsed magnetic fields

2021 ◽  
pp. 22-29 ◽  
Author(s):  
I. Zolotarevskii
Keyword(s):  
Magnetic Field ◽  
Martensitic Transformation ◽  
Magnetic Fields ◽  
Temperature Dependence ◽  
Strong Magnetic Field ◽  
Low Temperatures ◽  
Strong Dependence ◽  
Magnetic Interaction ◽  
Iron Alloys ◽  
Pulsed Magnetic Fields

Purpose of work. To ascertain the causes of the abnormally large displacement of the martensitic point in steels and iron alloys in strong pulsed magnetic fields at low temperatures. Research methods. Generalization of experimental and theoretical investigations of the strong magnetic field influence on the martensitic transformation in steels and iron alloys, taking into account the magnetic state of austenite. The obtained results. The distributions of the martensitic point displacement ΔMS from the content of the main component - iron and the temperature of the martensitic γ → α- transformation beginning (martensitic point MS) in different experiments are obtained. It is shown that the obtained temperature dependence ΔMS(MS) in a strong magnetic field at low temperatures decomposes into two components, one of which correlates with the generalized Clapeyron-Clausius equations, and the other is opposite to it. In addition, it was found that steels and alloys with intense γ → α- transformation in a magnetic field contain at least 72.5% iron (wt), which at low temperatures in the fcc structure is antiferromagnetic. Scientific novelty. The anomalous temperature dependence of the distribution ΔMS(MS) in a strong magnetic field is explained on the basis of quantum representations of the magnetic interaction of atoms in the Fe-Ni system. This effect is associated with a number of other invar effects, in particular, with an abnormally large spontaneous and forced magnetostriction, a strong dependence of the resulting exchange integral on the interatomic distance. The point of view according to which in these alloys in a magnetic field γ → α- transformation occurs by the type of “magnetic first kind phase transformation” is substantiated. It is assumed that the nucleation of the martensitic phase in a magnetic field occurs in (at) local regions of γ- phase with disoriented atomic magnetic moments (with high compression and increased forced magnetostriction). Practical value. The information obtained in this work provides grounds for explaining the kinetic features of the transformation of austenite into martensite in steels and iron alloys.

Effect of Pulsed Magnetic Fields on Cholesterol and Tryglyceride Levels in Rats Study of Field Intensity and Length of Exposure

1996 ◽  
Vol 51 (7-8) ◽  
pp. 603-606 ◽  
Author(s):  
A. Bellossi ◽  
V. Pouvreau-Quillien ◽  
C. Rocher ◽  
M. Ruelloux
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Field Intensity ◽  
Plasma Levels ◽  
Pulsed Magnetic Field ◽  
Pulsed Magnetic Fields ◽  
Minute Exposure ◽  
Linear Effect ◽  
Non Linear Effect ◽  
Non Linear

Abstract In a previous work a decrease in cholesterol and triglyceride plasma levels was observed in rats 24 hours after their exposure to a 12 Hz 6 mT pulsed magnetic field (PMF). This time, a study of intensity effects of a 12 Hz PMF for a sixty-minute exposure and of length of exposure for a 12 Hz 6 mT PMF took place. Non-linear effect-dose relationships were ob­ served for the PMF intensity as well as for the length of exposure used. The highest decreases in cholesterol and triglyceride levels were obtained after to a sixty-minute exposure with 1.5 mT and 12 mT.

Magnetic phase transitions by strong, pulsed magnetic fields at low temperatures in CuxZn1−xCr2Se4

1981 ◽  
Vol 2 (1) ◽  
pp. 67-73 ◽  
Author(s):  
S. Juszczyk ◽  
J. Krok ◽  
I. Okońska-Kozłowska ◽  
H. Broda ◽  
J. Warczewski ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Magnetic Fields ◽  
Low Temperatures ◽  
Magnetic Phase ◽  
Magnetic Phase Transitions ◽  
Pulsed Magnetic Fields

Science and Techniques Using Pulsed Magnetic Fields

MRS Bulletin ◽  
1993 ◽  
Vol 18 (8) ◽  
pp. 44-49 ◽  
Author(s):  
J.J.M. Franse ◽  
N. Miura
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
High Field ◽  
Materials Science ◽  
Copper Wire ◽  
Field Research ◽  
Outer Diameter ◽  
Electricity Grid ◽  
Pulsed Magnet ◽  
Time Profiles

In this article, we examine materials behavior in the magnetic field region from about 40 T to 500 T using pulsed magnet technology. Examples of materials science using two different pulsed magnet technologies are described in this article.Semicontinuous MagnetsSince the late 1960s, the University of Amsterdam has operated a semicontinuous magnetic field installation that produces magnetic fields up to 40 T with typical time constants of about one second. The magnet coil is constructed from hard-drawn copper wire with a reinforcement cylinder of maraging steel positioned at roughly one third of the outer diameter. Before operation, the coil is cooled to 30 K by cold neon gas. The power for this installation is taken directly from a 10 kV connection to the public electricity grid. By means of a thyristor-based power control system, highly flexible field-time profiles can be realized: step-wise pulses can be generated with field levels constant within 10−4 during 100 ms; linearly increasing and decreasing fields as well as exponentially ripple-free decreasing fields are other examples of standard field-time profiles. Among the measuring techniques frequently used are magnetization, magneto-transport, quantum oscillations, relaxation phenomena, etc. Temperatures at which experiments can be performed range from 400 mK to room temperature. In the Netherlands, the Amsterdam High Field Facility has recently been combined with the High Magnetic Field Laboratory in Nijmegen, where static magnetic fields up to 30 T are produced in hybrid magnet systems, to form the Amsterdam-Nijmegen Magnet Laboratory (ANML). The high field research of ANML comprises semiconductors, magnetism in transition-metal compounds, heavy-fermion physics, superconductors, organic conductors, and magnetic separation. We present here a few selected topics.

High-magnetic-field study of magnetic and transport properties of hole-doped NdBaCo2O5+δ

2011 ◽  
Vol 84 (18) ◽  
Author(s):  
E. S. Vlakhov ◽  
N. Kozlova ◽  
L. S. Lobanovskii ◽  
R. Wawryk ◽  
K. A. Nenkov
Keyword(s):  
Magnetic Field ◽  
Field Study ◽  
Transport Properties ◽  
High Magnetic Field

TUNING OF THE MAGNETIC FIELD INDUCED SHARP BAND-EDGE OPTICAL ABSORPTION IN EUROPIUM CHALCOGENIDES

2004 ◽  
Vol 18 (27n29) ◽  
pp. 3813-3816 ◽  
Author(s):  
A. B. HENRIQUES ◽  
L. K. HANAMOTO ◽  
E. TER HAAR ◽  
E. ABRAMOF ◽  
A. Y. UETA ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Optical Absorption ◽  
Low Temperatures ◽  
Optical Transition ◽  
Band Edge ◽  
Near Band Edge ◽  
High Magnetic Fields ◽  
Sharp Band ◽  
The Magnetic Field

The near band-edge polarized optical optical absortion spectra of EuTe at low temperatures and high magnetic fields were investigated. The samples were grown by MBE on BaF 2 substrates, and the thickness varied in the 0.18-2.0 μm range. At high magnetic fields, the well-known 4f7→4f65d(t2g) optical transition splits into two well resolved lines at σ+ and two lines for σ-. These lines can be described by localized transitions tunable by the d-f exchange interaction, with a quadratic dependence on the intensity of the external magnetic field. Comparative measurements of the magnetization and the optical absorption as a function temperature provides a further test of the model of a localized excitation extending over a few lattice sites.

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