Optical tests for broken time-reversal symmetry in the cuprate superconductors

Miscellaneous · Wed Jan 01 00:00:00 EST 1992

OSTI ID:6988327

Spielman, S R

Optical measurements have been made on YBa[sub 2]Cu[sub 3]O[sub 7] and Bi[sub 2]Sr[sub 2]CaCu[sub 2]O[sub 8] to search for both spontaneous Faraday rotation (in transmission) and spontaneous Kerr rotation (reflection). The observation of these magneto-optical effects near Tc would be a clear indication that the superconductivity in the cuprate superconductors can be explained by a theory which predicts broken time-reversal (T) symmetry. In particular, the [open quotes]any on[close quotes] model of these materials predicts that T symmetry will be broken spontaneously as the material is cooled. The magneto-optical effects are expected to be quite small compared to the birefringence of the material. A method has been developed that uses a fiber-optic Sagnac interferometer to search for the magneto-optic signal. Incident upon the samples are two counter-propagating circularly polarized beams, whose electric fields have opposite time dependence. The interferometer detects Faraday or Kerr rotation by measuring the difference in phase between these beams after they have interacted with the sample. Because it is immune to birefringence in the sample, this method is superior to simply analyzing the polarization state of a single beam. Transmission experiments at 1060 nm wavelength were done with a modified fiber-optic gyroscope (a type of Sagnac interferometer). The nonreciprocal phase shift observed in the cuprates was less than the sensitivity (2 [mu]rad). A 670 nm interferometer was constructed to look for these effects in the visible portion of the spectrum, where other researchers have witnessed unusual polarization effects.Both reflection and transmission measurements at this wavelength indicate there are no magneto-optic effects to a sensitivity of 5 [mu]rad. This technique has been applied successfully to study ferromagnetic phase transitions in films of EuO and Gd.

• Research Organization: Stanford Univ., CA (United States)
• OSTI ID: 6988327
• Resource Relation: Other Information: Thesis (Ph.D.)
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CUPRATES
FARADAY EFFECT
KERR EFFECT
HIGH-TC SUPERCONDUCTORS
ANYONS
BARIUM OXIDES
BISMUTH OXIDES
CALCIUM OXIDES
EUROPIUM OXIDES
GADOLINIUM
INTERMETALLIC COMPOUNDS
MAGNETO-OPTICAL EFFECTS
STRONTIUM OXIDES
SYMMETRY
TRANSITION TEMPERATURE
YTTRIUM OXIDES
ALKALINE EARTH METAL COMPOUNDS
ALLOYS
BARIUM COMPOUNDS
BISMUTH COMPOUNDS
CALCIUM COMPOUNDS
CHALCOGENIDES
COPPER COMPOUNDS
DIELECTRIC PROPERTIES
ELECTRICAL PROPERTIES
ELEMENTS
EUROPIUM COMPOUNDS
METALS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
QUASI PARTICLES
RARE EARTH COMPOUNDS
RARE EARTHS
STRONTIUM COMPOUNDS
SUPERCONDUCTORS
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
360207* - Ceramics
Cermets
& Refractories- Superconducting Properties- (1992-)
360204 - Ceramics
Cermets
& Refractories- Physical Properties
665411 - Basic Superconductivity Studies- (1992-)