Quantum Coherence and Random Fields at Mesoscopic Scales

Technical Report · Tue Mar 01 00:00:00 EST 2016

DOI:https://doi.org/10.2172/1240767· OSTI ID:1240767

Rosenbaum, Thomas F. ^[1]

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1. Univ. of Chicago, IL (United States)

We seek to explore and exploit model, disordered and geometrically frustrated magnets where coherent spin clusters stably detach themselves from their surroundings, leading to extreme sensitivity to finite frequency excitations and the ability to encode information. Global changes in either the spin concentration or the quantum tunneling probability via the application of an external magnetic field can tune the relative weights of quantum entanglement and random field effects on the mesoscopic scale. These same parameters can be harnessed to manipulate domain wall dynamics in the ferromagnetic state, with technological possibilities for magnetic information storage. Finally, extensions from quantum ferromagnets to antiferromagnets promise new insights into the physics of quantum fluctuations and effective dimensional reduction. A combination of ac susceptometry, dc magnetometry, noise measurements, hole burning, non-linear Fano experiments, and neutron diffraction as functions of temperature, magnetic field, frequency, excitation amplitude, dipole concentration, and disorder address issues of stability, overlap, coherence, and control. We have been especially interested in probing the evolution of the local order in the progression from spin liquid to spin glass to long-range-ordered magnet.

• Research Organization: Univ. of Chicago, IL (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• DOE Contract Number: FG02-99ER45789
• OSTI ID: 1240767
• Report Number(s): DOE-CHICAGO-45789; TRN: US1600675
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
SPIN
NEUTRON DIFFRACTION
EXCITATION
RANDOMNESS
SPIN GLASS STATE
MAGNETIC FIELDS
DIPOLES
FLUCTUATIONS
INFORMATION
LIQUIDS
NONLINEAR PROBLEMS
QUANTUM ENTANGLEMENT
TEMPERATURE DEPENDENCE
TUNNEL EFFECT
AMPLITUDES
CONTROL
EVOLUTION
PROBABILITY
SENSITIVITY
STABILITY
STORAGE
WALLS
FERROMAGNETIC MATERIALS
DOMAIN STRUCTURE
FANO FACTOR
FREQUENCY DEPENDENCE