title: Frequency-crossing phonon spectrometer techniques.
abstract: An ac technique for measuring magnetothermal conductivities using frequency crossing has been developed and shows a 13-fold increase in signal-to-noise ratio over the conventional dc technique. The ac technique employs low-frequency field modulation coupled with phase-sensitive detection and a 45-fold improvement in signal-to-noise ratio may be obtained by modulation over the half-width of the frequency crossing signal. A further increase of approximately 3 would be obtainable by increasing the modulation frequency and overcoming technical problems. The limit of detection and instrument revolution may be as low as 10 in. spins and a few megahertz, respectively.
authors.affiliation: Department of Physics, University of Nottingham, University Park, Nottingham NG7 2RD, England.
authors.forename: M N
authors.initials: MN
authors.lastname: Wybourne
authors.forename: D J
authors.initials: DJ
authors.lastname: Jefferies
authors.forename: L J
authors.initials: LJ
authors.lastname: Challis
authors.forename: A A
authors.initials: AA
authors.lastname: Ghazi