Revealing the anisotropic thermal conductivity using time-resolved magneto-optical Kerr effect

Jie Zhu, Dustin M. Lattery, Junyang Chen, Delin Zhang, Xiaokun Gu, Haechan Park, Dawei Tang, Mo Li, Xu Du, Ronggui Yang, Jian Ping Wang, Xiaojia Wang

Research output: Contribution to journalConference articlepeer-review

Abstract

Ultrafast thermo-magneto-optical effect upon femtosecond laser excitation, has enabled new capabilities in the thermal characterization of nanomaterials. In this work, we demonstrate time-resolved magneto-optical Kerr effect (TR-MOKE) as an advanced thermal characterization technique for studying the anisotropic thermal properties of materials. The original factors of the MOKE signal are revealed for four magnetic transducers, including TbFe, GdFeCo, Co/Pd, and CoFe/Pt. A figure of merit is proposed to evaluate the performance of magnetic transducers by examining the improvement of the signal-to-noise ratio (SNR) in TR-MOKE measurements. Excellent agreement between experimental TR-MOKE signals and computed figure of merit is achieved for all four magnetic transducers. We observe the best SNR for TR-MOKE measurements with rare-earth transition metal (RE-TM)-based TbFe and GdFeCo transducers. As an example, we conduct TR-MOKE measurements on a model system of single crystalline black phosphorus (BP) flakes using the optimal TbFe transducer. The measured anisotropic thermal conductivity of BP along three primary crystalline directions well corroborates first-principles predictions. Further, we demonstrate that TR-MOKE, compared with the standard time-domain thermoreflectance, offers an enhanced measurement sensitivity to the in-plane thermal conductivity of materials, and meanwhile is immune to other uncertainties in the transducer properties. Thus, the overall uncertainties of TR-MOKE for in-plane thermal measurements can be significantly improved.

Original languageEnglish (US)
Pages (from-to)2575-2582
Number of pages8
JournalInternational Heat Transfer Conference
Volume2018-August
DOIs
StatePublished - 2018
Event16th International Heat Transfer Conference, IHTC 2018 - Beijing, China
Duration: Aug 10 2018Aug 15 2018

Keywords

  • Anisotropic thermal transport
  • Black phosphorus
  • Micro/nanoscale thermal measurement and simulation
  • Thermophysical properties
  • Time-resolved magneto-optical Kerr effect
  • Ultrafast laser spectroscopy

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