Optical properties of the iron-based superconductor LiFeAs single crystal
We have measured the reflectivity spectra of the LiFeAs ( T _c = 17.6 K) single crystal in the temperature range from 4 to 300 K. In the superconducting (SC) state ( T < T _c ), the clean opening of the optical absorption gap was observed below 25 cm ^−1 , indicating an isotropic full gap form...
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| Format: | Article |
| Language: | English |
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IOP Publishing
2013-01-01
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| Series: | New Journal of Physics |
| Online Access: | https://doi.org/10.1088/1367-2630/15/7/073029 |
| _version_ | 1797751395019915264 |
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| author | Byeong Hun Min Jong Beom Hong Jae Hyun Yun Takuya Iizuka Shin-ichi Kimura Yunkyu Bang Yong Seung Kwon |
| author_facet | Byeong Hun Min Jong Beom Hong Jae Hyun Yun Takuya Iizuka Shin-ichi Kimura Yunkyu Bang Yong Seung Kwon |
| author_sort | Byeong Hun Min |
| collection | DOAJ |
| description | We have measured the reflectivity spectra of the LiFeAs ( T _c = 17.6 K) single crystal in the temperature range from 4 to 300 K. In the superconducting (SC) state ( T < T _c ), the clean opening of the optical absorption gap was observed below 25 cm ^−1 , indicating an isotropic full gap formation. In the normal state ( T > T _c ), the optical conductivity spectra display typical metallic behavior with the Drude-type spectra at low frequencies, but we found that the introduction of the two Drude components best fits the data, indicating the multiband nature of this compound. A theoretical analysis of the low-temperature data ( T = 4 K < T _c ) also suggests that two SC gaps best fit the data and their values were estimated as Δ _1 = 3.3 meV and Δ _2 = 1.59 meV, respectively. Using the Ferrell–Glover–Tinkham sum rule and dielectric function ϵ _1 ( ω ), the plasma frequency of the SC condensate ( ω _ps ) is consistently estimated to be 6665 cm ^−1 , implying that about 65% of the free carriers of the normal state condense into the SC condensate. To investigate the various interband transition processes (for ω > 200 cm ^−1 ), we have also performed the local-density approximation band calculation and calculated the optical spectra of the interband transitions. This theoretical result provided qualitative agreement with the experimental data below 4000 cm ^−1 . |
| first_indexed | 2024-03-12T16:48:53Z |
| format | Article |
| id | doaj.art-af51dc33aa9a47458250fc9ae395d209 |
| institution | Directory Open Access Journal |
| issn | 1367-2630 |
| language | English |
| last_indexed | 2024-03-12T16:48:53Z |
| publishDate | 2013-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | New Journal of Physics |
| spelling | doaj.art-af51dc33aa9a47458250fc9ae395d2092023-08-08T11:27:44ZengIOP PublishingNew Journal of Physics1367-26302013-01-0115707302910.1088/1367-2630/15/7/073029Optical properties of the iron-based superconductor LiFeAs single crystalByeong Hun Min0Jong Beom Hong1Jae Hyun Yun2Takuya Iizuka3Shin-ichi Kimura4Yunkyu Bang5Yong Seung Kwon6Department of Emerging Materials Science, Daegu Gyeongbuk Institute of Science and Technology (DGIST) , Daegu 711-873, Republic of KoreaDepartment of Physics, Sungkyunkwan University , Suwon 440-746, Republic of KoreaDepartment of Physics, Chonnam National University , Kwangju 500-757, Republic of KoreaSchool of Physical Sciences, The Graduate University for Advanced Studies , Okazaki 444-8585, JapanSchool of Physical Sciences, The Graduate University for Advanced Studies , Okazaki 444-8585, Japan; UVSOR Facility, Institute for Molecular Science , Okazaki 444-8585, JapanDepartment of Physics, Chonnam National University , Kwangju 500-757, Republic of Korea; Asia Pacific Center for Theoretical Physics, Pohang 790-784, Republic of KoreaDepartment of Emerging Materials Science, Daegu Gyeongbuk Institute of Science and Technology (DGIST) , Daegu 711-873, Republic of KoreaWe have measured the reflectivity spectra of the LiFeAs ( T _c = 17.6 K) single crystal in the temperature range from 4 to 300 K. In the superconducting (SC) state ( T < T _c ), the clean opening of the optical absorption gap was observed below 25 cm ^−1 , indicating an isotropic full gap formation. In the normal state ( T > T _c ), the optical conductivity spectra display typical metallic behavior with the Drude-type spectra at low frequencies, but we found that the introduction of the two Drude components best fits the data, indicating the multiband nature of this compound. A theoretical analysis of the low-temperature data ( T = 4 K < T _c ) also suggests that two SC gaps best fit the data and their values were estimated as Δ _1 = 3.3 meV and Δ _2 = 1.59 meV, respectively. Using the Ferrell–Glover–Tinkham sum rule and dielectric function ϵ _1 ( ω ), the plasma frequency of the SC condensate ( ω _ps ) is consistently estimated to be 6665 cm ^−1 , implying that about 65% of the free carriers of the normal state condense into the SC condensate. To investigate the various interband transition processes (for ω > 200 cm ^−1 ), we have also performed the local-density approximation band calculation and calculated the optical spectra of the interband transitions. This theoretical result provided qualitative agreement with the experimental data below 4000 cm ^−1 .https://doi.org/10.1088/1367-2630/15/7/073029 |
| spellingShingle | Byeong Hun Min Jong Beom Hong Jae Hyun Yun Takuya Iizuka Shin-ichi Kimura Yunkyu Bang Yong Seung Kwon Optical properties of the iron-based superconductor LiFeAs single crystal New Journal of Physics |
| title | Optical properties of the iron-based superconductor LiFeAs single crystal |
| title_full | Optical properties of the iron-based superconductor LiFeAs single crystal |
| title_fullStr | Optical properties of the iron-based superconductor LiFeAs single crystal |
| title_full_unstemmed | Optical properties of the iron-based superconductor LiFeAs single crystal |
| title_short | Optical properties of the iron-based superconductor LiFeAs single crystal |
| title_sort | optical properties of the iron based superconductor lifeas single crystal |
| url | https://doi.org/10.1088/1367-2630/15/7/073029 |
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