Time Domain Thermoreflectance
TDTR is an optical pump/probe method capable of rapidly characterizing thermal transport properties. TDTR measures how the temperature of the surface evolves as a function of time as heat flows from the surface of the material. The thermal conductivity and heat-capacity of the sample strongly affects the rate of thermal transport away from the surface, and therefore strong affects its temperature evolution. By solving an analytical solution to the heat diffusion equation, we can quantify thermal properties of bulk materials, thin-film materials, 2D-materials, or interfaces.
Time Resolved Magneto Optic Kerr Effect
When studying ultrafast magnetic dynamics, or spin-transport in metal multilayers, temperature induced changes in a metal’s reflectance are not a sufficient probe of the physics. Therefore, we take advantage of the time-resolved polar magneto-optic Kerr effect to detect transient changes in magnetization. Spin-orbit coupling in metals gives rise to a Kerr rotation of the polarization of reflected light. We detect this rotation in polarization with nano-radian precision through the combination of a Wollaston prism and balanced detector.
Time Domain Terahertz Spectroscopy
In addition to exciting materials and interrogating their response with visible and near infrared radiation, our lab has the capability to utilize short pulses of THz radiation in our pump/probe experiments. Electromagnetic radiation in the terahertz frequency range is a powerful spectroscopic tool that allows us to resonantly excite, probe, and control the vibrational, electronic, and magnetic modes of materials. We use photoconductive Auston switches to generate transient THz radiation in a wave guide structure. The coplanar waveguide allows us to focus the THz radiation to micron dimensions, thereby achieving massive THz intensities difficult to achieve with free-space radiation.
Magneto Optic Kerr Effect Microscopy
Polar MOKE microscopy together with an electromagnet allows us to directly image magnetic domains in magnetic films.
Reactive Magnetron Sputter Deposition
We use an ultra-high vacuum ATC Orion series confocal magnetron sputter deposition system from AJA to synthesize metal multilayer systems. The system possesses 5 sputter guns and is equipped with mass-flow-controllers to enable reactive sputter deposition of materials such as TiN and VO2. A SiC heater capable of reaching 850°C provides temperature control before, during, or after growth.
Electrical Probe Station
We use a Signatone four-point probe station together with a Keithley 2410 source meter to characterize the electrical transport properties of our metal films.