The derivation of effective spin Hamiltonians and the origin of the magnetic field induced transition in orthormbic La sub 2 CuO sub 4

Conference · Tue Jan 01 04:00:00 EST 1991

OSTI ID:5645396

Coffey, D

La{sub 2}CuO{sub 4} undergoes a magnetic field induced transition in a field of {approx}5.7 Tesla at low temperatures. The origin of this transition is the Dzyaloshinskii-Moriya interaction which is present in effective spin Hamiltonians for systems of sufficiently low symmetry, and, which leads to weak ferromagnetism in the CuO planes in La{sub 2}CuO{sub 4}. It is shown here how this interaction depends on symmetry and how its form changes with structural phase transitions which occur in compounds closely related to La{sub 2}CuO{sub 4}. These different forms of the interaction lead to different properties in magnetic fields. I also discuss how the approach presented here of determining an effective spin Hamiltonian from symmetry is related to the determination of terms in the free expansion close to a second order phase transition. It is pointed out that the present approach may be extended to itinerant systems and 1 take UPt{sub 3} as an example. 28 refs., 4 figs.

• Research Organization: Los Alamos National Lab., NM (USA)
• Sponsoring Organization: DOE; USDOE, Washington, DC (USA)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 5645396
• Report Number(s): LA-UR-91-1680; CONF-9105151--5; ON: DE91013743
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
656100 -- Condensed Matter Physics-- Superconductivity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ANISOTROPY
CHALCOGENIDES
COPPER COMPOUNDS
COPPER OXIDES
FERROMAGNETISM
HAMILTONIANS
LANTHANUM COMPOUNDS
LANTHANUM OXIDES
MAGNETIC FIELDS
MAGNETISM
MATHEMATICAL OPERATORS
ORIENTATION
OXIDES
OXYGEN COMPOUNDS
QUANTUM OPERATORS
RARE EARTH COMPOUNDS
SPIN FLIP
SPIN ORIENTATION
TRANSITION ELEMENT COMPOUNDS