Meissner Effect: History of Development and Novel Aspects

The discovery of the Meissner (Meissner–Ochsenfeld) effect in 1933 was an incontestable turning point in the history of superconductivity. First, it demonstrated that superconductivity is an unknown before equilibrium state of matter, thus allowing to use the power of thermodynamics for its study. This provided a justification for the two-fluid model of Gorter and Casimir, a seminal thermodynamic theory founded on a postulate of zero entropy of the superconducting (S) component of conduction electrons. Second, the Meissner effect demonstrated that, apart from zero electric resistivity, the S phase is also characterized by zero magnetic induction. The latter property is used as a basic postulate in the theory of F. and H. London, which underlies the understanding of electromagnetic properties of superconductors. Here the experimental and theoretical aspects of the Meissner effect are reviewed. The reader will see that, in spite of almost nine decades age, the London theory still contains questions, the answers to which can lead to a revision of the standard picture of the Meissner state (MS) and, if so, of other equilibrium superconducting states. An attempt is made to take a fresh look at electrodynamics of the MS and try to work out with the issues associated with this the most important state of all superconductors. It is shown that the concept of Cooper's pairing along with the Bohr–Sommerfeld quantization condition allows one to construct a semi-classical theoretical model consistently addressing properties of the MS and beyond, including non-equilibrium properties of superconductors caused by the total current. As follows from the model, the three “big zeros” of superconductivity (zero resistance, zero induction and zero entropy) have equal weight and grow from a single root: quantization of the angular momentum of paired electrons. The model predicts some yet unknown effects. If confirmed, they can help in studies of microscopic properties of all superconductors. Preliminary experimental results suggesting the need to revise the standard picture of the MS are presented.

Holographic p-wave superconductor with $$C^2F^2$$ correction

Via numerical and analytical method, we construct the holographic p-wave conductor/superconductor model with $$C^2F^2$$C2F2 correction (where $$C^2F^2=C_{\mu \nu }^{\alpha \beta }C_{ \alpha \beta }^{\mu \nu }F_{\rho \sigma }F^{\rho \sigma }$$C2F2=CμναβCαβμνFρσFρσ, and $$C_{\mu \nu }^{\alpha \beta }$$Cμναβ and $$F_{\rho \sigma }$$Fρσ denotes the Weyl tensor and gauge field strength, respectively.)in the four-dimensional Schwarzschild-AdS black hole, and mainly study the effects of $$C^2F^2$$C2F2 correction parameter denoted by $$\gamma $$γ on the properties of superconductors. The results show that for all values of the $$C^2F^2$$C2F2 parameter, there always exists a critical temperature below which the vector hair appears. Meanwhile, the critical temperature increases with the improving $$C^2F^2$$C2F2 parameter $$\gamma $$γ, which suggests that the improving $$C^2F^2$$C2F2 parameter enhances the superconductor phase transition. Furthermore, at the critical temperature, the real part of conductivity reproduces respectively a Drude-like peak and an obviously pronounced peak for some value of nonvanishing $$C^2F^2$$C2F2 parameter. At the low temperature, a clear energy gap can be observed at the intermediate frequency and the ratio of the energy gap to the critical temperature decreases with the increasing $$C^2F^2$$C2F2 parameter, which is consistent with the effect of the $$C^2F^2$$C2F2 parameter on the critical temperature. In addition, the analytical results agree well with the numerical results, which means that the analytical Sturm–Liouville method is still reliable in the grand canonical ensemble.

Sintesis dan Analisis Penambahan Doping Magnesium (Mg) pada Material Superkonduktor FeSe dengan Metode Reaksi Padatan dalam Tabung Tertutup

[ID] Ketergantungan manusia terhadap teknologi memasuki Revolusi Industri 4.0 sangat tinggi. Contoh penerapan inovasi di bidang teknologi informasi salah satunya adalah superkomputer dari material superkonduktor. Material superkonduktor identik dengan material non ferromagnetik karena sifatnya diamagnetis sempurna. Namun, sejak ditemukannya material superkonduktor berbasis logam ferromagnetik, penelitian terus dikembangkan, salah satunya material FeSe. Beberapa parameter yang perlu diperhatikan pada pembuatan material FeSe untuk memperoleh sifat superkonduktor terbaiknya diantaranya komposisi stoikiometri, penambahan doping, dan proses pembuatan material FeSe seperti proses pemaduan dan sintering. Dalam penelitian ini, pengaruh variasi doping Mg akan dianalisis terhadap sifat superkonduktor, morfologi, dan fasa yang terbentuk pada material superkonduktor FeSe. Material FeSe dibuat dengan metode reaksi padatan dalam tabung tertutup (Powder in Sealed Tube) secara insitu. Temperatur sintering yang digunakan 845⁰C yang ditahan selama 6 jam, dengan kenaikan temperatur 7⁰C/menit dari temperatur kamar, dan laju pendinginan normalizing. Kandidat material superkonduktor terbaik terdapat pada sampel Mg0.01Fe0.99Se. Didapatkan Temperatur kritis (Tc)onset = 15.42 K dan Tczero = 5.4 K. Morfologi sampel menunjukkan kristalisasi besar. Lalu, persentase fraksi volume fasa superkonduktornya juga merupakan yang terbesar yaitu 81.99%. [EN] Human dependence on technology into the Industrial Revolution 4.0 is very high. Example, the application of innovations in information technology is supercomputer from superconducting materials. Superconducting materials are identical from non-ferromagnetic materials because tend perfectly diamagnetic. However, since ferromagnetic-metal-based superconducting material discovered, research continues to be developed, like FeSe material. Some parameters that need to be considered in making FeSe material to obtain the best superconductor properties include stoichiometric composition, doping addition, and process of making FeSe materials like synthesis and sintering treatment. In this study, the effect of Mg-doped variations will be analyzed towards properties of superconductors, morphology, and phases formed in FeSe superconducting materials. MgxFe1-xSe made by solid-state reaction method in sealed tube (Powder in Sealed Tube) “insituely”. The sintering temperature used 845⁰C which held for 6 hours, with 7⁰C/minute temperature rise from room-temperature and normalizing cooling rate used. The best candidate superconducting material came from Mg0.01Fe0.99Se, obtained critical temperature (Tc)onset = 15.42 K, and Tczero = 5.4 K. Sample morphology shows a large crystallization. Then, the percentage fraction of the superconducting phase was also the largest, which is 81.99%.

Analisis Penambahan Doping Magnesium (Mg) pada Material Superkonduktor FeSe dengan Metode Reaksi Padatan dalam Tabung Tertutup

[ID] Ketergantungan manusia terhadap teknologi memasuki Revolusi Industri 4.0 sangat tinggi. Contoh penerapan inovasi di bidang teknologi informasi salah satunya adalah superkomputer dari material superkonduktor. Material superkonduktor identik dengan material non ferromagnetik karena sifatnya diamagnetis sempurna. Namun, sejak ditemukannya material superkonduktor berbasis logam ferromagnetik, penelitian terus dikembangkan, salah satunya material FeSe. Beberapa parameter yang perlu diperhatikan pada pembuatan material FeSe untuk memperoleh sifat superkonduktor terbaiknya diantaranya komposisi stoikiometri, penambahan doping, dan proses pembuatan material FeSe seperti proses pemaduan dan sintering. Dalam penelitian ini, pengaruh variasi doping Mg akan dianalisis terhadap sifat superkonduktor, morfologi, dan fasa yang terbentuk pada material superkonduktor FeSe. Material FeSe dibuat dengan metode reaksi padatan dalam tabung tertutup (Powder in Sealed Tube) secara insitu. Temperatur sintering yang digunakan 845⁰C yang ditahan selama 6 jam, dengan kenaikan temperatur 7⁰C/menit dari temperatur kamar, dan laju pendinginan normalizing. Kandidat material superkonduktor terbaik terdapat pada sampel Mg0.01Fe0.99Se. Didapatkan Temperatur kritis (Tc)onset = 15.42 K dan Tczero = 5.4 K. Morfologi sampel menunjukkan kristalisasi besar. Lalu, persentase fraksi volume fasa superkonduktornya juga merupakan yang terbesar yaitu 81.99%. [EN] Human dependence on technology into the Industrial Revolution 4.0 is very high. Example, the application of innovations in information technology is supercomputer from superconducting materials. Superconducting materials are identical from non-ferromagnetic materials because tend perfectly diamagnetic. However, since ferromagnetic-metal-based superconducting material discovered, research continues to be developed, like FeSe material. Some parameters that need to be considered in making FeSe material to obtain the best superconductor properties include stoichiometric composition, doping addition, and process of making FeSe materials like synthesis and sintering treatment. In this study, the effect of Mg-doped variations will be analyzed towards properties of superconductors, morphology, and phases formed in FeSe superconducting materials. MgxFe1-xSe made by solid-state reaction method in sealed tube (Powder in Sealed Tube) “insituely”. The sintering temperature used 845⁰C which held for 6 hours, with 7⁰C/minute temperature rise from room-temperature and normalizing cooling rate used. The best candidate superconducting material came from Mg0.01Fe0.99Se, obtained critical temperature (Tc)onset = 15.42 K, and Tczero = 5.4 K. Sample morphology shows a large crystallization. Then, the percentage fraction of the superconducting phase was also the largest, which is 81.99%.