76 research outputs found
Experimental Study of Reference Frequency and Time Scales Transmission Systems via Optical Fiber
The way of reference frequency and time scales transmission via optical fiber is describes in the article. Transmission system is designed to transfer reference signals from clock to remote objectβs users. It uses two standard communication fiber optical links. One optical channel is used for transfer of reference frequency signal. Second channel is used to compare time scales of remote objects. The results of experimental studies of the transmission uncertainly of reference frequency and time signals using fiber-optic communication lines are listed. The method of radio frequency reference signal transmission by optical fiber line is represented. The scheme of electronic compensation of reference 100 MHz signal phase perturbations in optical fiber is described. The experimental results of Allan deviation measurements of 100 MHz reference signal transmitted to the remote end of fiber line 100 km long are presented
Magnetization and specific heat of TbFe3(BO3)4: Experiment and crystal field calculations
We have studied the thermodynamic properties of single-crystalline
TbFe3(BO3)4. Magnetization measurements have been carried out as a function of
magnetic field (up to 50 T) and temperature up to 350K with the magnetic field
both parallel and perpendicular to the trigonal c-axis of the crystal. The
specific heat has been measured in the temperature range 2-300K with a magnetic
field up to 9 T applied parallel to the c-axis. The data indicate a structural
phase transition at 192 K and antiferromagnetic spin ordering at 40 K. A
Schottky anomaly is present in the specific heat data around 20 K, arising due
to two low-lying energy levels of the Tb3+ ions being split by f-d coupling.
Below TN magnetic fields parallel to the c-axis drive a spin-flop phase
transition, which is associated with a large magnetization jump. The highly
anisotropic character of the magnetic susceptibility is ascribed mainly to the
Ising-like behavior of the Tb3+ ions in the trigonal crystal field. We describe
our results in the framework of an unified approach which is based on
mean-field approximation and crystal-field calculations.Comment: 10 pages, 10 figures, 20 references, accepted by Phys. Rev.
Temperature Behavior of the Antiferromagnetic Susceptibility of Nanoferrihydrite from the Measurements of the Magnetization Curves in Fields of up to 250 kOe
Π’Π΅ΠΊΡΡ ΡΡΠ°ΡΡΠΈ Π½Π΅ ΠΏΡΠ±Π»ΠΈΠΊΡΠ΅ΡΡΡ Π² ΠΎΡΠΊΡΡΡΠΎΠΌ Π΄ΠΎΡΡΡΠΏΠ΅ Π² ΡΠΎΠΎΡΠ²Π΅ΡΡΡΠ²ΠΈΠΈ Ρ ΠΏΠΎΠ»ΠΈΡΠΈΠΊΠΎΠΉ ΠΆΡΡΠ½Π°Π»Π°
Pulsed Field-Induced Magnetization Switching in Antiferromagnetic Ferrihydrite Nanoparticles
The dynamic magnetization switching of ferrihydrite nanoparticles has been investigated by a pulsed magnetometer technique in maximum fields Hmax of up to 130 kOe with pulse lengths of 4, 8, and 16 ms. Ferrihydrite exhibits antiferromagnetic ordering and defects cause the uncompensated magnetic moment in nanoparticles; therefore, the behavior typical of magnetic nanoparticles is observed. The dynamic hysteresis loops measured under the above-mentioned conditions show that the use of pulsed fields significantly broadens the temperature region of existence of the magnetic hysteresis and the coercivity can be governed by varying the maximum field and pulse length. This behavior is resulted from the relaxation effects typical of conventional ferro- and ferrimagnetic nanoparticles and the features typical of antiferromagnetic nanoparticles
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