極低温ラマン顕微鏡は、高解像度極低温共焦点レーザ走査型顕微鏡とラマン分光系の組み合わせによりものです。attoRAMANを使うことで最大15Tの磁場中で、極低温下の顕微ラマン分光及び、ラマンイメージを得ることができます。attoRAMANはラマン用レーザー発振器（532nmまたは633nm対応）、冷却裏面照射型CCDの採用、先進のコントローラ/ソフトウェアが付属します。

attoRAMANでは試料の粗動機構としてxyzピエゾステージを使用しており、5mmの可動範囲があります。さらにピエゾスキャナーは、50μmX50μm（室温）、 30μmX30μm（4K）のスキャン範囲があります。ラマンイメージは、試料上をラスタースキャンを行いつつ各点でラマン分光測定を行います。

The figure to the left shows magneto-Raman measurements recorded at 4 K on an exfoliated single crystal of natural graphite with unprecedented spatial resolution (approx. 0.5 μm), while sweeping the magnetic field from -9 T to +9 T. The data were recorded on a single graphene flake and demonstrate the crossing of the E2g phonon energy with the electron-hole separation between the valence and conduction Landau levels
(-N,+M) of the Dirac cone. Resonant hybridization of the E2g phonon is a specific signature of graphene flakes which display very rich Raman scattering spectra varying strongly as function of magnetic field [1].

[1] C. Faugeras et al., Phys. Rev. Lett. 107, 036807 (2011); (attocube application labs, 2011; work in cooperation with C. Faugeras, P. Kossacki, and M. Potemski, LNCM I – Grenoble, CNRS_UJF_UPS_INSA France)

The combination of confocal Raman microscopy and magnetic fields at 4 K yields the opportunity to investigate and tune the electron-phonon interaction in graphene and few-layer graphene. In particular, excitations between Landau levels can resonantly couple to the Raman active long wavelength optical phonon (G-phonon), when their energies are matched, resulting in magneto- phonon resonances (MPRs). Such resonances at ±3.7 T are presented in the figure and highlighted by arrows. The details of the coupling depend on various material properties of the investigated graphene layer. From the MPRs, device parameters such as the electron-phonon coupling constant or the Fermi velocity of the charge carriers can be extracted. Interestingly for low charge carrier doping, the Fermi velocity shows signatures of many-bod interaction effects [2].

[2] Nat Comms, Nature Publishing Group, 2015, 6, 8429