Accession Number : ADA306382

Title :   Quantum Tunneling of Magnetization.

Descriptive Note : Final rept. 1 Apr 92-30 Sep 95,

Corporate Author : CITY COLL NEW YORK DEPT OF PHYSICS

Personal Author(s) : Sarachik, Myriam P.

PDF Url : ADA306382

Report Date : 30 SEP 1995

Pagination or Media Count : 8

Abstract : The objective of these investigations was to study the magnetic properties of a collection of small magnetic particles or magnetized domains with special attention to detecting and documenting the occurence of macroscopic quantum tunneling of magnetization. Magnetized small particles are the basic elements used for magnetic storage, and our studies are important from a technological points of view: quantum-mechanical tunneling of the magnetization of small particles sets the ultimate limit on the reliability of magnetic storage and an upper limit on storage density. Experimentally, we succeeded in observing thermally assisted, field-tuned resonant tunneling between quantum spin states in a macroscopic-sized sample of the molecular magnetic material, manganese acetate. The magnetic properties of horse-spleen ferritin were also investigated. Theoretical studies included investigations of tunneling in random magnets, the introduction of the concept of a 'critical state', theoretical studies of antiferromagnetic grains with uncompensated sublattices, and the crossover from antiferromagnetic to ferromagnetic tunneling.

Descriptors :   *TUNNELING(ELECTRONICS), *QUANTUM ELECTRONICS, *MAGNETIZATION, MAGNETIC FIELDS, MOLECULAR STATES, QUANTUM THEORY, MAGNETS, RELIABILITY(ELECTRONICS), FERROMAGNETIC MATERIALS, ACETATES, MAGNETIC MATERIALS, FERROMAGNETISM, SPIN STATES, MOLECULAR ENERGY LEVELS, ANTIFERROMAGNETISM, PARAMAGNETISM, MAGNETIC DISKS, MANGANESE COMPOUNDS.

Subject Categories : Electricity and Magnetism
      Quantum Theory and Relativity

Distribution Statement : APPROVED FOR PUBLIC RELEASE