To date we have studied a variety of material systems, including bulk semiconductors and quantum wells, epitaxial quantum dots and colloidal nanocrystals, carbon nanotubes and quantum wires, complex oxides, and quantum spin ladder compounds.
Polarization-resolved optical studies can often be used as a proxy for direct magnetization measurements. In particular, magneto-optical effects such as magnetic circular dichroism (MCD) and optical Faraday rotation (FR) depend explicitly on breaking of time-reversal symmetry. Typically this means the presence of magnetization. We often use MCD and FR to infer and study magnetization in materials ranging from semiconductors to colloidal quantum dots to complex oxides to organic molecules (see references below). Often the sensitivity exceeds that of conventional (eg, SQUID) magnetometry, and moreover the detailed spectral dependence of the signal can pinpoint specific mechanisms and energy scales.
- 0-8 Tesla superconducting split-coil magnet with direct optical access and a variable temperature insert (1.5-300 K)
- variety of Xenon lamp and tungsten-halogen lamps, coupled with scanning spectrometers to produce wavelength-tunable light
- variety of polarization modulators to modulate between right and left-circularly polarized light
- avalanche photodiode detectors
Detectors and Spectrometers:
- UV-VIS CCD array dectector (back-thinned, LN2-cooled; Princeton Instruments)
- IR array detector (InGaAs array, LN2-cooled; Princeton Instruments)
- Multichannel-plate PMT an avalanche photodiodes for time-resolved PL
- 300 mm & 500 mm spectrometers (Acton)
- Ti:sapphire (both ultrafast pulsed & CW ring). Frequency doubling available.
- Helium-cadmium (442 nm and 325 nm)
- CW dye
- variety of laser diode sources (532 nm, 405 nm, 635 nm, 785 nm, 1550 nm, etc.)
- Tungsten-halogen and Xe lamps for broadband white light
- pulsed whitelight generation via photonic crystal fiber
Images & Sample Data
Click on an image for larger view and details.
- 7/8 T magnet with multiple optical setups 7/8 T magnet with multiple optical setups
- Spectrometer input. Spectrometer input.
- Laser-assisted Xenon lamp. Laser-assisted Xenon lamp.
- Spectrometer. Spectrometer.
W.D. Rice, et al, Persistent optically induced magnetization in oxygen-deficient strontium titanate, Nat. Mater. 13 (2014) Read online
K. Alberi, et al, Magnetic-field induced delocalized to localized transformation in GaAs:N, Phys. Rev. Lett. 110 (2013) Read online
L. G. Booshehri, et al, Circular polarization dependent cyclotron resonance in large-area graphene in ultrahigh magnetic fields, Phys. Rev. B 85 (2012) Read online
T. Greidig, et al, Substrate-controlled ferromagnetism in iron phthalocyanine films due to one-dimensional iron chains, Phys. Rev. B 86 (2012) Read online
A. Pandley, et al, Long-lived photo-induced magnetization in copper-doped ZnSe/CdSe core/shell nanocrystals, Nat. Nanotechnol. 7 (2012) Read online
D.A. Bussian, et al, Tunable magnetic exchange interactions in Mn-doped inverted core-shell ZnSe/CdSe nanocrystals, Nat. Mater. 8 (2009) Read online
J. Shaver, et al, Magneto-optical spectroscopy of highly-aligned carbon nanotubes: Identifying the role of threading magnetic flux, Phys. Rev. B Rapid-Comm 78 (2008) Read online
S.A. Crooker, et al, Tuning alloy disorder in diluted magnetic semiconductors in high fields to 89 tesla, Appl. Phys. Lett. 90 (2007) Read online
S. Zaric, et al, Excitons in carbon nanotubes with broken time-reversal symmetry, Phys. Rev. Lett. 96 (2006) Read online