scholarly journals Quantum-classical crossover of the escape rate in a biaxial spin system with an arbitrarily directed magnetic field

2000 ◽  
Vol 61 (17) ◽  
pp. 11618-11624 ◽  
Author(s):  
Chang-Soo Park ◽  
Sahng-Kyoon Yoo ◽  
Dal-Ho Yoon
Keyword(s):  
Magnetic Field ◽  
Spin System ◽  
Escape Rate

scholarly journals Quantum-classical transition of the escape rate of a uniaxial spin system in an arbitrarily directed field

1998 ◽  
Vol 57 (21) ◽  
pp. 13639-13654 ◽  
Author(s):  
D. A. Garanin ◽  
X. Martínez Hidalgo ◽  
E. M. Chudnovsky
Keyword(s):  
Spin System ◽  
Escape Rate ◽  
Classical Transition

scholarly journals Magnetic-field induced quantum phase transition and critical behavior in a gapped spin system

2007 ◽  
Vol 310 (2) ◽  
pp. 1352-1354 ◽  
Author(s):  
F. Yamada ◽  
T. Ono ◽  
M. Fujisawa ◽  
H. Tanaka ◽  
T. Sakakibara
Keyword(s):  
Magnetic Field ◽  
Phase Transition ◽  
Quantum Phase Transition ◽  
Spin System ◽  
Critical Behavior ◽  
Quantum Phase

scholarly journals Planetary magnetic field control of ion escape from weakly magnetized planets

2019 ◽  
Vol 488 (2) ◽  
pp. 2108-2120 ◽  
Author(s):  
Hilary Egan ◽  
Riku Jarvinen ◽  
Yingjuan Ma ◽  
David Brain
Keyword(s):  
Magnetic Field ◽  
Effective Interaction ◽  
Three Dimensional ◽  
Power Laws ◽  
Wind Pressure ◽  
Escape Rate ◽  
Opening Angle ◽  
Plasma Environment ◽  
Ion Escape ◽  
Planetary Magnetic Field

ABSTRACT Intrinsic magnetic fields have long been thought to shield planets from atmospheric erosion via stellar winds; however, the influence of the plasma environment on atmospheric escape is complex. Here we study the influence of a weak intrinsic dipolar planetary magnetic field on the plasma environment and subsequent ion escape from a Mars-sized planet in a global three-dimensional hybrid simulation. We find that increasing the strength of a planet’s magnetic field enhances ion escape until the magnetic dipole’s standoff distance reaches the induced magnetosphere boundary. After this point increasing the planetary magnetic field begins to inhibit ion escape. This reflects a balance between shielding of the Southern hemisphere from ‘misaligned’ ion pickup forces and trapping of escaping ions by an equatorial plasmasphere. Thus, the planetary magnetic field associated with the peak ion escape rate is critically dependent on the stellar wind pressure. Where possible we have fit power laws for the variation of fundamental parameters (escape rate, escape power, polar cap opening angle, and effective interaction area) with magnetic field, and assessed upper and lower limits for the relationships.

PULSE-FIELD EXPERIMENTS ON THE SPIN-LATTICE INTERACTION IN LOW-DIMENSIONAL SPIN SYSTEMS

2002 ◽  
Vol 16 (20n22) ◽  
pp. 3369-3372
Author(s):  
B. WOLF ◽  
S. ZHERLITSYN ◽  
S. SCHMIDT ◽  
B. LÜTHI ◽  
M. LANG
Keyword(s):  
Magnetic Field ◽  
Spin System ◽  
Field Experiments ◽  
Resonant Interaction ◽  
Quantum Spin ◽  
Spin Systems ◽  
Pulse Field ◽  
Quantum Spin System ◽  
Magnetic Excitations ◽  
Low Dimensional

Low-dimensional spin systems reveal new and unexpected physical phenomena such as distinct plateaus in the magnetization as a function of magnetic field. In this paper we present ultrasonic measurements for the quasi-two-dimensional spin system SrCu2(BO3)2 in magnetic fields up to 50 T. From this technique we obtained detailed information about the spin state, the magnetic excitations and their interaction with phonons. The dimerized quantum-spin system SrCu2(BO3)2 exhibits plateaus in the magnetization and shows surprisingly strong magneto-elastic effects as a function of temperature and magnetic field. The pronounced elastic anomalies indicate a resonant interaction between the sound wave and the magnetic excitations.

One Pulse Spin-locking in NQR

1996 ◽  
Vol 51 (5-6) ◽  
pp. 357-362 ◽  
Author(s):  
B. Bandyopadhyay ◽  
G. B. Furman ◽  
S. D. Goren ◽  
C. Korn ◽  
A. L Shames
Keyword(s):  
Magnetic Field ◽  
Single Crystal ◽  
Spin System ◽  
Cuprous Oxide ◽  
Resonance Condition ◽  
Excitation Power ◽  
Effective Field ◽  
Spin Locking ◽  
Long Pulse ◽  
Theoretical Results

Abstract The response of a quadrupolar spin system in zero applied magnetic field to a long rf pulse, for both single crystal and polycrystalline samples possessing broad Lorentzian-shaped resonance lines has been studied. The dependencies of magnetization on frequency offset, linewidth and power are investigated both theoretically and experimentally. The problem of the effective field direction in both single crystal and polycrystalline samples is also discussed. For a polycrystalline cuprous oxide (Cu2O) sample it is observed that the magnetization after a long pulse in on-resonance condition does not become zero for time t ≫ T2 , in agreement with theoretical results. It has also been shown that the magnetization increases with increase in the width of the resonance line as well as with the decrease in the excitation power.

scholarly journals Large discrete jumps observed in the transition between Chern states in a ferromagnetic topological insulator

2016 ◽  
Vol 2 (7) ◽  
pp. e1600167 ◽  
Author(s):  
Minhao Liu ◽  
Wudi Wang ◽  
Anthony R. Richardella ◽  
Abhinav Kandala ◽  
Jian Li ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Metastable State ◽  
Large Fraction ◽  
Surface States ◽  
Anomalous Hall Effect ◽  
Escape Rate ◽  
Zero Magnetic Field ◽  
Hall Resistance ◽  
Edge States ◽  
Longitudinal Resistance

A striking prediction in topological insulators is the appearance of the quantized Hall resistance when the surface states are magnetized. The surface Dirac states become gapped everywhere on the surface, but chiral edge states remain on the edges. In an applied current, the edge states produce a quantized Hall resistance that equals the Chern numberC= ±1 (in natural units), even in zero magnetic field. This quantum anomalous Hall effect was observed by Changet al. With reversal of the magnetic field, the system is trapped in a metastable state because of magnetic anisotropy. We investigate how the system escapes the metastable state at low temperatures (10 to 200 mK). When the dissipation (measured by the longitudinal resistance) is ultralow, we find that the system escapes by making a few very rapid transitions, as detected by large jumps in the Hall and longitudinal resistances. Using the field at which the initial jump occurs to estimate the escape rate, we find that raising the temperature strongly suppresses the rate. From a detailed map of the resistance versus gate voltage and temperature, we show that dissipation strongly affects the escape rate. We compare the observations with dissipative quantum tunneling predictions. In the ultralow dissipation regime, two temperature scales (T1~ 70 mK andT2~ 145 mK) exist, between which jumps can be observed. The jumps display a spatial correlation that extends over a large fraction of the sample.

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