講演情報
[10a-N303-4]Linear Photogalvanic Effect in Centrosymmetric Dirac Semimetals
〇小林 裕太1、小沢 耀弘1、河口 真志1、Wang Shunzhen1、宮崎 稜大1、藤原 宏平2、島野 亮1、塚﨑 敦1、岡 隆史1、林 将光1 (1.東大、2.立大)
キーワード：
ディラック半金属、フォトガルバニック効果、Bismuth
Photogalvanic effects provide a direct probe of symmetry breaking, offering insights into charge transport and light-matter interactions. Recently, the helicity-dependent photogalvanic effect, also known as the circular photogalvanic effect (CPGE), has been extensively studied in topological materials due to its direct connection to spin-momentum-locked topological states. For the experimental evaluation of CPGE, the following phenomenological equation is commonly used:
I/P = Csin(2α) + L1sin(4α) + L2cos(4α) + D,
where I/P is the photocurrent normalized by laser power and α is the rotation angle of the quarter waveplate used to control the helicity of the incident light. The first term represents CPGE, reflecting the response to circularly polarized light. The second term is attributed to the linear photogalvanic effect (LPGE), with the L1 term known to exhibit a relatively large value in topological materials. However, the mechanism behind L1 remains poorly understood. The third and fourth terms typically represent polarization-dependent absorption and photo-thermal effects, respectively.
In this study, we investigated the origin of the L1 term using wire-shaped thin films of centrosymmetric Dirac semimetals (Bi and Co3Sn2S2) fabricated via photolithography. Photocurrent responses were measured under different illumination conditions. In the presentation, we discuss material dependence and symmetry considerations relevant to the origin of the L1 term.
I/P = Csin(2α) + L1sin(4α) + L2cos(4α) + D,
where I/P is the photocurrent normalized by laser power and α is the rotation angle of the quarter waveplate used to control the helicity of the incident light. The first term represents CPGE, reflecting the response to circularly polarized light. The second term is attributed to the linear photogalvanic effect (LPGE), with the L1 term known to exhibit a relatively large value in topological materials. However, the mechanism behind L1 remains poorly understood. The third and fourth terms typically represent polarization-dependent absorption and photo-thermal effects, respectively.
In this study, we investigated the origin of the L1 term using wire-shaped thin films of centrosymmetric Dirac semimetals (Bi and Co3Sn2S2) fabricated via photolithography. Photocurrent responses were measured under different illumination conditions. In the presentation, we discuss material dependence and symmetry considerations relevant to the origin of the L1 term.