金飚兵
低温太赫兹光谱技术在材料科学、化学和药学中的应用,生物组织的太赫兹光谱成像,太赫兹检测器,超导薄膜的微波和太赫兹表征。
个性化签名
- 姓名:金飚兵
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学术头衔:
博士生导师, 教育部“新世纪优秀人才支持计划”入选者
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学科领域:
制糖技术
- 研究兴趣:低温太赫兹光谱技术在材料科学、化学和药学中的应用,生物组织的太赫兹光谱成像,太赫兹检测器,超导薄膜的微波和太赫兹表征。
金飚兵,1967年生,最高学历:研究生 学位:博士 职称:教授,博士导师。1986年,1991年和1995年毕业于南京大学电子科学与工程系,获学士、硕士和博士学位,现为电子科学与工程系教授、博士生导师。1998.9到2000.7在新加坡国立大学物理系(NUS)从事超导微波器件的研究;从2000.8到2004.12在德国于利希研究中心(Research Center Juelich, 该中心教授 P. Grunberg 荣获2007度诺贝尔物理学奖)作为客座研究员从事超导薄膜的微波和太赫兹表征方面的研究;从2005.2 到2006.9 受弗莱芒基金会资助在比利时基督教鲁汶大学从事高频超导磁通整流效应的研究。在2006年11月加入南京大学电子科学与工程系。2007年入选教育部“新世纪优秀人才支持计划”和江苏省高校“青蓝工程中青年学术带头人”计划。 近年来参加了国家973和863等多个研究项目。发表SCI收录论文30篇。
主要研究方向:低温太赫兹光谱技术在材料科学、化学和药学中的应用,生物组织的太赫兹光谱成像,太赫兹检测器,超导薄膜的微波和太赫兹表征。
主要成果:1) 建立了低温 THz光谱测量系统,大大拓宽了 THz光谱技术的应用范围,使之成为一个研究材料,生物分子,药物分子和超导材料的有效手段。2)在MgB2 超导薄膜的微波和太赫兹表征方面,发现了反常电导率峰,揭示了MgB2 的双能隙特性在相干效应上的特殊表现;另外测得薄膜的表面电阻在THz波段小于正常金属, 表明超导无源器件在太赫兹波段仍然具有优越性。由于该工作的原创性和重要性,做出了原创性的工作,结果发表在PRL,PRB和APL(均为第一作者)。
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5
【期刊论文】Microwave and Terahertz Surface Resistance of MgB2 Thin Films
金飚兵, B. B. Jin, T. Dahm, F. Kadlec, P. Kuzel, A. I. Gubin, Eun-Mi Choi, Hyun Jung Kim, Sung-IK Lee, W. N. Kang, S. F. Wang, Y. L. Zhou, A. V. Pogrebnyakov, , J. M. Redwing, X. X. Xi, and N. Klein
Journal of Superconductivity and Novel Magnetism, Vol.19, Nos.7-8, November 2006,-0001,():
-1年11月30日
The knowledge of the surface resistance Rs of superconducting thin film at microwave and terahertz (THz) regions is significant to design, make and assess superconducting microwave and THz electronic devices. In this paper we reported the Rs of MgB2 films at microwave and THz measured with sapphire resonator technique and the time-domain THz spectroscopy, respectively. Some interesting results are revealed in the following: (1) A clear correlation is found between Rs and normal-state resistivity right above Tc, ρ0, i.e., Rs decreases almost linearly with the decrease of ρ0. (2) A low residual Rs, less than 50 μ at 18 GHz is achieved by different deposition techniques. In addition, between 10 and 14 K, MgB2 has the lowest Rs compared with two other superconductors Nb3Sn and the high-temperature superconductor YBa2Cu3O7−δ(YBCO). (3) From THz measurement it is found that the Rs of MgB2 up to around 1 THz is lower than that of copper and YBCO at the temperature below 25 K. (4) The frequency dependence of Rs follows ωn, where ω is angular frequency, and n is power index. However, n changes from 1.9 at microwave to 1.5 at THz. The above results clearly give the evidences that MgB2 thin film, compared with other superconductors, is of advantage to make superconducting circuits working in the microwave and THz regions.
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【期刊论文】Anomalous Coherence Peak in the Microwave Conductivity of c-Axis Oriented MgB2 Thin Films
金飚兵, B. B. Jin, T. Dahm, A. I. Gubin, Eun-Mi Choi, Hyun Jung Kim, Sung-IK Lee, W. N. Kang, and N. Klein
PHYSICAL REVIEWLETTERS 19 SEPTEMBER 2003 VOLUME 91, NUMBER 12,-0001,():
-1年11月30日
The temperature dependence of the real part of the microwave complex conductivity at 17.9 GHz obtained from surface impedance measurements of two c-axis oriented MgB2 thin films reveals a pronounced maximum at a temperature around 0.6 times the critical temperature. Calculations in the frame of a two-band model based on Bardeen-Cooper-Schrieffer (BCS) theory suggest that this maximum corresponds to an anomalous coherence peak resembling the two-gap nature of MgB2. Our model assumes there is no interband impurity scattering and a weak interband pairing interaction, as suggested by band structure calculations. In addition, the observation of a coherence peak indicates that the band is in the dirty limit and dominates the total conductivity of our films.
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金飚兵, B. B. Jin* and N. Klein, W. N. Kang, Hyeong-Jin Kim, Eun-Mi Choi, and Sung-Ik Lee, T. Dahm, K. Maki
PHYSICAL REVIEW B66, 104521 (2002),-0001,():
-1年11月30日
We have measured the temperature dependence of the microwave surface impedance Zs=Rs+iωμoλ of two c-axis oriented MgB2 films employing dielectric resonator techniques. The temperature dependence of the magnetic-field penetration depth λ determined by a sapphire dielectric resonator at 17.9 GHz can be well fitted from 5K close to Tc by the standard BCS integral expression assuming the reduced energy gap △(0)/kTc to be as low as 1.13 and 1.03 for the two samples. For the penetration depth at zero temperatures, values of 102 and 107 nm were determined from the fit. Our results clearly indicate the s-wave character of the order parameter. A similar fit of the penetration depth data was obtained with an anisotropic s-wave BCS model. Within this model we had to assume a prolate order parameter, having a large gap value in the c-axis direction and a small gap within the ab plane. This is in contrast to recent fits of the anisotropic s-wave model to upper critical-field data, where an oblate order parameter had to be used, and raises interesting questions about the nature of the superconducting state in MgB2. A rutile dielectric resonator was employed to obtain the temperature dependence of Rs with high accuracy. Below about Tc/2, Rs (T) 2Rs (5K) exhibits an exponential temperature dependence with a reduced energy gap consistent with that determined from the penetration depth data. The Rs value at 4.2K was found to be as low as 19 mVat 7.2 GHz, which is comparable with a high-temperature superconducting copper oxide thin film.
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【期刊论文】Anomalous Coherence Peak in the Microwave Conductivity of c-Axis Oriented MgB2 Thin Films
金飚兵, B. B. Jin, T. Dahm, A. I. Gubin, Eun-Mi Choi, Hyun Jung Kim, Sung-IK Lee, W. N. Kang, and N. Klein
VOLUME 91, NUMBER 12 PHYSICAL REVIEW LETTERS 19 SEPTEMBER 2003,-0001,():
-1年11月30日
The temperature dependence of the real part of the microwave complex conductivity at 17.9 GHz obtained from surface impedance measurements of two c-axis oriented MgB2 thin films reveals a pronounced maximum at a temperature around 0.6 times the critical temperature. Calculations in the frame of a two-band model based on Bardeen-Cooper-Schrieffer (BCS) theory suggest that this maximum corresponds to an anomalous coherence peak resembling the two-gap nature of MgB2. Our model assumes there is no interband impurity scattering and a weak interband pairing interaction, as suggested by band structure calculations. In addition, the observation of a coherence peak indicates that the band is in the dirty limit and dominates the total conductivity of our films.
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金飚兵, B. B. Jin* and N. Klein, T. Dahm, K. Maki
PHYSICAL REVIEW B 66, 104521(2002),-0001,():
-1年11月30日
We have measured the temperature dependence of the microwave surface impedance Zs5Rs1ivm0l of two c-axis oriented MgB2 films employing dielectric resonator techniques. The temperature dependence of the magnetic-field penetration depth l determined by a sapphire dielectric resonator at 17.9 GHz can be well fitted from 5 K close to Tc by the standard BCS integral expression assuming the reduced energy gap D(0)/kTc to be as low as 1.13 and 1.03 for the two samples. For the penetration depth at zero temperatures, values of 102 and 107 nm were determined from the fit. Our results clearly indicate the s-wave character of the order parameter. A similar fit of the penetration depth data was obtained with an anisotropic s-wave BCS model. Within this model we had to assume a prolate order parameter, having a large gap value in the c-axis direction and a small gap within the ab plane. This is in contrast to recent fits of the anisotropic s-wave model to upper critical-field data, where an oblate order parameter had to be used, and raises interesting questions about the nature of the superconducting state in MgB2 . A rutile dielectric resonator was employed to obtain the temperaturedependence of Rs with high accuracy. Below about Tc/2, Rs(T)2Rs(5 K) exhibits an exponential temperature dependence with a reduced energy gap consistent with that determined from the penetration depth data. The Rs value at 4.2 K was found to be as low as 19 mV at 7.2 GHz, which is comparable with a high-temperature superconducting copper oxide thin film.
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