Second{\_}harmonic thermal conductivity of LSCO in magnetic fields

We describe a second harmonic technique to probe the thermal conductivity of LSCO with superconductivity suppressed by high magnetic fields. The technique is suitable for the high noise environment of pulsed magnets. By subtracting the thermal conductivity in field and at zero field, we obtain information about the temperature dependence of the order parameter. Work performed under the auspices of the National High Magnetic Field Laboratory