Evolution of Shape and Volume Fraction of Superconducting Domains with Temperature and Anion Disorder in (TMTSF)<sub>2</sub>ClO<sub>4</sub>
In highly anisotropic organic superconductor (TMTSF)<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>2</mn></msub></semantics></math></inline-formula>ClO<inline-formula><math display=&q...
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MDPI AG
2021-01-01
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| author | Kaushal K. Kesharpu Vladislav D. Kochev Pavel D. Grigoriev |
| author_facet | Kaushal K. Kesharpu Vladislav D. Kochev Pavel D. Grigoriev |
| author_sort | Kaushal K. Kesharpu |
| collection | DOAJ |
| description | In highly anisotropic organic superconductor (TMTSF)<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>2</mn></msub></semantics></math></inline-formula>ClO<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>4</mn></msub></semantics></math></inline-formula>, superconducting (SC) phase coexists with metallic and spin-density wave phases in the form of domains. Using the Maxwell-Garnett approximation (MGA), we calculate the volume ratio and estimate the shape of these embedded SC domains from resistivity data at various temperature and anion disorder, controlled by the cooling rate or annealing time of (TMTSF)<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>2</mn></msub></semantics></math></inline-formula>ClO<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>4</mn></msub></semantics></math></inline-formula> samples. We found that the variation of cooling rate and of annealing time affect differently the shape of SC domains. In all cases the SC domains have oblate shape, being the shortest along the interlayer <i>z</i>-axis. This contradicts the widely assumed filamentary superconductivity along the <i>z</i>-axis, used to explain the anisotropic superconductivity onset. We show that anisotropic resistivity drop at the SC onset can be described by the analytical MGA theory with anisotropic background resistance, while the anisotropic <inline-formula><math display="inline"><semantics><msub><mi>T</mi><mi>c</mi></msub></semantics></math></inline-formula> can be explained by considering a finite size and flat shape of the samples. Due to a flat/needle sample shape, the probability of percolation via SC domains is the highest along the shortest sample dimension (<i>z</i>-axis), and the lowest along the sample length (<i>x</i>-axis). Our theory can be applied to other heterogeneous superconductors, where the size <i>d</i> of SC domains is much larger than the SC coherence length <inline-formula><math display="inline"><semantics><mi>ξ</mi></semantics></math></inline-formula>, e.g., cuprates, iron-based or organic superconductors. It is also applicable when the spin/charge-density wave domains are embedded inside a metallic background, or vice versa. |
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| last_indexed | 2024-03-09T04:32:37Z |
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| spelling | doaj.art-1b037461f45f46c1a855bc3dfefd38a52023-12-03T13:33:26ZengMDPI AGCrystals2073-43522021-01-011117210.3390/cryst11010072Evolution of Shape and Volume Fraction of Superconducting Domains with Temperature and Anion Disorder in (TMTSF)<sub>2</sub>ClO<sub>4</sub>Kaushal K. Kesharpu0Vladislav D. Kochev1Pavel D. Grigoriev2Department of Theoretical Physics and Quantum Technology, National University of Science and Technology “MISiS”, 119049 Moscow, RussiaDepartment of Theoretical Physics and Quantum Technology, National University of Science and Technology “MISiS”, 119049 Moscow, RussiaDepartment of Theoretical Physics and Quantum Technology, National University of Science and Technology “MISiS”, 119049 Moscow, RussiaIn highly anisotropic organic superconductor (TMTSF)<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>2</mn></msub></semantics></math></inline-formula>ClO<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>4</mn></msub></semantics></math></inline-formula>, superconducting (SC) phase coexists with metallic and spin-density wave phases in the form of domains. Using the Maxwell-Garnett approximation (MGA), we calculate the volume ratio and estimate the shape of these embedded SC domains from resistivity data at various temperature and anion disorder, controlled by the cooling rate or annealing time of (TMTSF)<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>2</mn></msub></semantics></math></inline-formula>ClO<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>4</mn></msub></semantics></math></inline-formula> samples. We found that the variation of cooling rate and of annealing time affect differently the shape of SC domains. In all cases the SC domains have oblate shape, being the shortest along the interlayer <i>z</i>-axis. This contradicts the widely assumed filamentary superconductivity along the <i>z</i>-axis, used to explain the anisotropic superconductivity onset. We show that anisotropic resistivity drop at the SC onset can be described by the analytical MGA theory with anisotropic background resistance, while the anisotropic <inline-formula><math display="inline"><semantics><msub><mi>T</mi><mi>c</mi></msub></semantics></math></inline-formula> can be explained by considering a finite size and flat shape of the samples. Due to a flat/needle sample shape, the probability of percolation via SC domains is the highest along the shortest sample dimension (<i>z</i>-axis), and the lowest along the sample length (<i>x</i>-axis). Our theory can be applied to other heterogeneous superconductors, where the size <i>d</i> of SC domains is much larger than the SC coherence length <inline-formula><math display="inline"><semantics><mi>ξ</mi></semantics></math></inline-formula>, e.g., cuprates, iron-based or organic superconductors. It is also applicable when the spin/charge-density wave domains are embedded inside a metallic background, or vice versa.https://www.mdpi.com/2073-4352/11/1/72organic superconductorsBeechgard saltsMaxwell-Garnett approximationhigh-Tc |
| spellingShingle | Kaushal K. Kesharpu Vladislav D. Kochev Pavel D. Grigoriev Evolution of Shape and Volume Fraction of Superconducting Domains with Temperature and Anion Disorder in (TMTSF)<sub>2</sub>ClO<sub>4</sub> Crystals organic superconductors Beechgard salts Maxwell-Garnett approximation high-Tc |
| title | Evolution of Shape and Volume Fraction of Superconducting Domains with Temperature and Anion Disorder in (TMTSF)<sub>2</sub>ClO<sub>4</sub> |
| title_full | Evolution of Shape and Volume Fraction of Superconducting Domains with Temperature and Anion Disorder in (TMTSF)<sub>2</sub>ClO<sub>4</sub> |
| title_fullStr | Evolution of Shape and Volume Fraction of Superconducting Domains with Temperature and Anion Disorder in (TMTSF)<sub>2</sub>ClO<sub>4</sub> |
| title_full_unstemmed | Evolution of Shape and Volume Fraction of Superconducting Domains with Temperature and Anion Disorder in (TMTSF)<sub>2</sub>ClO<sub>4</sub> |
| title_short | Evolution of Shape and Volume Fraction of Superconducting Domains with Temperature and Anion Disorder in (TMTSF)<sub>2</sub>ClO<sub>4</sub> |
| title_sort | evolution of shape and volume fraction of superconducting domains with temperature and anion disorder in tmtsf sub 2 sub clo sub 4 sub |
| topic | organic superconductors Beechgard salts Maxwell-Garnett approximation high-Tc |
| url | https://www.mdpi.com/2073-4352/11/1/72 |
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