scholarly journals Bistable memory effect in chromium oxide junctions

2002 ◽  
Vol 746 ◽  
Author(s):  
A. Sokolov ◽  
C.-S. Yang ◽  
E. Ovtchenkov ◽  
L. Yuan ◽  
S.-H. Liou ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electrical Properties ◽  
External Magnetic Field ◽  
High Speed ◽  
Excitation Pulse ◽  
Zero Field ◽  
Zero Bias ◽  
In Series ◽  
Iv Curves ◽  
Zero Bias Anomaly

ABSTRACTMagnetotransport properties of granular CrO2 /Cr2O3 films made of CrO2 crystals covered by 1– 2 nm native insulating Cr2O3 are presented. Electrical properties of a limited number of grains measured in series and parallel (10 to 15 grains) reveal intergrain tunneling characteristics. At lowest temperatures, a well pronounced zero bias anomaly indicates that impurities in the junctions block the electronic flow.Hysteresis in the IV curves are observed at intermediate temperatures on zero-field cooled samples. Changing the polarity of a short excitation pulse (100ns) of amplitude smaller than 1 V triggers a change in the zero-bias resistance by 10–50%. These states are stable and well reproducible in the temperature interval ranging from 100K to 250K. Applying an external magnetic field cancels the IV hysteresis. The resistance of the devices in the kΩ range, the potential high-speed for writing and reading the resistance sate, make these systems interesting candidates for magnetic non-volatile memories.

EFFECT OF DISORDER ON THE ELECTRICAL PROPERTIES OF AMORPHOUS CONDUCTING CARBON FILMS: OBSERVANCE OF FIELD INDUCED METAL-INSULATOR TRANSITION?

2000 ◽  
Vol 14 (02n03) ◽  
pp. 224-229 ◽  
Author(s):  
V. MEENAKSHI ◽  
S. V. SUBRAMANYAM
Keyword(s):  
Magnetic Field ◽  
Electrical Properties ◽  
External Magnetic Field ◽  
Low Temperature ◽  
Carbon Films ◽  
Electronic Systems ◽  
Metal Insulator Transition ◽  
Preparation Temperature ◽  
Metal Insulator ◽  
Effect Of Disorder

In this work, the influence of disorder on the electrical properties (DC conductivity and Magnetoresistance) of amorphous conducting carbon films, prepared by the pyrolysis of Tetra chloro phthalic anhydride, is reported and discussed. The low temperature electrical properties are analyzed in terms of the various models developed for disordered electronic systems. The results indicate the possibility of a metal - insulator (M-I) transition, both as a function of preparation temperature and an external magnetic field.

scholarly journals Coherent emission from the stack of Josephson junctions with the non-uniform inductive interaction

2019 ◽  
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Gaussian Distribution ◽  
Josephson Junctions ◽  
Critical Currents ◽  
Collective Modes ◽  
Zero Field ◽  
Strong Emission ◽  
Inductive Interaction ◽  
Coherent Emission

During last decade, considerable efforts were made to achieve coherent emission from stacks of many Josephson junctions. It is known that strong emission from a junction in the presence of external magnetic field appears at the so-called Fiske steps in the IV-characteristic at voltages which correspond to frequencies of geometrical resonances. However, it is possible to obtain resonant steps in long junctions without external magnetic field. The periodical movement of fluxons is excited due to some disorder in the distribution of critical currents along junctions. The so-called zero-field steps are formed in the IV-curve due to the interaction of fluxons with oscillations of voltage at Josephson frequencies. We investigated numerically IV-characteristics and the dependence of the average square of ac voltage at the end of the stack of two long Josephson junctions on the average voltage. Junctions interacted inductively with each other. We introduced not only the Gaussian distribution of critical currents along junctions but also the Gaussian distribution of coefficients of the interaction between junctions (mutual inductances). Zero-field steps in the IV-characteristic were found at voltages which corresponded to frequencies of in-phase collective modes in the stack as well as to frequencies of uncoupled junctions. Zero-field steps appeared in the hysteretic region of the IV-curve. There appeared also jumps of voltage from the resistive branch to the zero-field step. We showed that there existed distributions of mutual inductances along junctions which provided jumps to voltages at which the average square of ac voltage at the end of the stack (which is proportional to power of emission) was larger than that for the stack with the uniform distribution of mutual inductances.

scholarly journals Investigation of the Arc Characteristics of Switching DC Arcs on Hydrogen Containing Gas Mixtures

2019 ◽  
Vol 6 (1) ◽  
pp. 69-72 ◽  
Author(s):  
D. Gonzalez ◽  
S. Gortschakow ◽  
S. Yu ◽  
F. Werner
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
High Speed ◽  
Gas Mixtures ◽  
High Speed Imaging ◽  
Arc Characteristics ◽  
Pressure Discharge ◽  
Model Chamber ◽  
Imaging And Spectroscopy ◽  
Dc Current

<p>The characteristics of switching DC current arcs in  hydrogen  containing gas mixtures under pressure were investigated using a model chamber. The switching device consists of an electro-mechanic double breaker unit with copper contacts. High-speed imaging and spectroscopy were used to observe and to characterize the switching arc. The experiments indicate how the dynamic interaction of an external magnetic field with a high-pressure discharge causes an elongation and twisting of the arc-channel and consequently a voltage increase. Comparative measurements with and without external magnetic field indicate a strong influence of this factor. Cu and N lines together with strongly broadened H lines were observed.</p>

Magnetic Prehistory in the Heat Capacity of the Low-Temperature Superconductors

2015 ◽  
Vol 233-234 ◽  
pp. 741-744
Author(s):  
Sergey Mikhailovich Podgornykh
Keyword(s):  
Magnetic Field ◽  
Heat Capacity ◽  
External Magnetic Field ◽  
Low Temperature ◽  
Temperature Dependence ◽  
Zero Magnetic Field ◽  
Zero Field ◽  
Ring Specimen ◽  
Trapped Flux ◽  
The Magnetic Field

Effect of the magnetic prehistory on the temperature dependence of the heat capacity of the superconducting Pb, La, Sn. has been studied. As soon as the external magnetic field riches the valueHext=HCthe superconductivity is completely destroyed. The trapped flux was produced in the ring specimen after the magnetic field was turned off atT<TC. We observed a difference of the value of the heat capacity between zero field cooled (ZFC) and field cooled (FC) states in zero magnetic field for the ring specimen. It is found that the FC heat capacity is smaller than the heat capacity both in the normal and in superconducting states.

scholarly journals Effect of External Magnetic Field on Long DC Arc Characteristics with Rng-shaped Anode

2021 ◽  
Vol 333 ◽  
pp. 03004
Author(s):  
Akio Hashizawa ◽  
Manabu Tanaka ◽  
Takayuki Watanabe ◽  
Tomohiro Koga
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
High Speed ◽  
Plasma Jet ◽  
Jet Flow ◽  
Critical Issue ◽  
Fluctuation Phenomena ◽  
High Speed Camera ◽  
Electrode Gap ◽  
Dc Arc

Fluctuation phenomena of plasma jet flow in an innovative long DC arc system with a ring-shaped anode were successfully clarified by a high-speed camera visualization. The long DC arc with long electrode gap distance more than 350 mm has been applied to gas decomposition due to its advantages of long plasma length, resulting in long residence time of treated gas. However, large heat loss at a conventional hemispherical-shaped anode was a critical issue in the long DC arc system. Therefore, the ring-shaped anode was utilized to convert large energy loss at the anode into the plasma jet flow. High-speed camera observation revealed the effect of external magnetic field on the fluctuation phenomena. Plasma jet fluctuates with the frequency of several tens Hz when the magnetic field was applied. These understanding of arc and plasma jet fluctuation enables to improve the capability of long DC arc system.

Vibration Characteristics of Magnetic Fluid Droplet Adsorbed to Magnetized Needlepoint in Alternating Magnetic Field

2012 ◽  
Vol 721 ◽  
pp. 108-113
Author(s):  
Sota Inomata ◽  
Seiichi Sudo ◽  
Hidemasa Takana ◽  
Hideya Nishiyama
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Magnetic Fluid ◽  
High Speed ◽  
Video Camera ◽  
Alternating Magnetic Field ◽  
Camera System ◽  
High Speed Video ◽  
High Speed Video Camera ◽  
Video Camera System

The dynamic behavior of a magnetic fluid droplet adsorbed to magnetized needlepoint in alternating magnetic field was studied with a high speed video camera system. The directions of alternating magnetic field were parallel and opposite to static magnetic field of magnetized needlepoint. It was found that the surface of magnetic fluid droplet responds to the external magnetic field in elongation and contraction. The frequency of magnetic fluid droplet oscillation was exactly same of the external magnetic field. The shape and instability oscillations of the magnetic fluid droplet were revealed experimentally.

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