{"title":"高锝铜氧化物超导体中伪缺口端点的起源","authors":"Jianhua Yang, Tao Li","doi":"10.1103/physrevb.110.024521","DOIUrl":null,"url":null,"abstract":"There are two seemingly unrelated puzzles about the cuprate superconductors. The first puzzle concerns the strong non-BCS behavior around <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>x</mi><mi>c</mi></msub></math>, the end point of the superconducting dome on the overdoped side, where the cuprate is believed to be well described by the Fermi-liquid theory. This is the most evident in the observed <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msub><mi>ρ</mi><mi>s</mi></msub><mrow><mo>(</mo><mn>0</mn><mo>)</mo></mrow><mo>−</mo><msub><mi>T</mi><mi>c</mi></msub></mrow></math> scaling and the large amount of uncondensed optical spectral weight at low energy. The second puzzle concerns the remarkable robustness of the <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>d</mi></math>-wave pairing against the inevitable disorder effect in such a doped system, which is also totally unexpected from the conventional BCS picture. Here we show that these two puzzles are deeply connected to the origin of a third puzzle about the cuprate superconductors, namely, the mysterious quantum critical behavior observed around <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msup><mi>x</mi><mo>*</mo></msup></math>, the so called pseudogap end point. Through a systematic variational Monte Carlo (VMC) study of the disordered 2D <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>t</mi><mo>−</mo><mi>J</mi></mrow></math> model from the resonating valence bond (RVB) perspective, we find that the <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>d</mi></math>-wave pairing in this model is remarkably more robust against the disorder effect than that in a conventional <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>d</mi></math>-wave BCS superconductor. We find that such remarkable robustness can be attributed to the spin-charge separation mechanism in the RVB picture, through which the <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>d</mi></math>-wave RVB pairing of the charge-neutral spinons becomes essentially immune to the disorder potential except for the secondary effect related to the modulation of the local doping level by the disorder. We propose that there exists a Mott transition at <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msup><mi>x</mi><mo>*</mo></msup></math>, where the RVB pairing in the underdoped regime is transmuted into the increasingly more BCS-like pairing for <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>x</mi><mo>></mo><msup><mi>x</mi><mo>*</mo></msup></mrow></math>, whose increasing fragility against the disorder effect leads to the non-BCS behavior and the ultimate suppression of superconductivity around <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>x</mi><mi>c</mi></msub></math>.","PeriodicalId":20082,"journal":{"name":"Physical Review B","volume":null,"pages":null},"PeriodicalIF":3.7000,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Origin of the pseudogap end point in high-Tc cuprate superconductors\",\"authors\":\"Jianhua Yang, Tao Li\",\"doi\":\"10.1103/physrevb.110.024521\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"There are two seemingly unrelated puzzles about the cuprate superconductors. The first puzzle concerns the strong non-BCS behavior around <math xmlns=\\\"http://www.w3.org/1998/Math/MathML\\\"><msub><mi>x</mi><mi>c</mi></msub></math>, the end point of the superconducting dome on the overdoped side, where the cuprate is believed to be well described by the Fermi-liquid theory. This is the most evident in the observed <math xmlns=\\\"http://www.w3.org/1998/Math/MathML\\\"><mrow><msub><mi>ρ</mi><mi>s</mi></msub><mrow><mo>(</mo><mn>0</mn><mo>)</mo></mrow><mo>−</mo><msub><mi>T</mi><mi>c</mi></msub></mrow></math> scaling and the large amount of uncondensed optical spectral weight at low energy. The second puzzle concerns the remarkable robustness of the <math xmlns=\\\"http://www.w3.org/1998/Math/MathML\\\"><mi>d</mi></math>-wave pairing against the inevitable disorder effect in such a doped system, which is also totally unexpected from the conventional BCS picture. Here we show that these two puzzles are deeply connected to the origin of a third puzzle about the cuprate superconductors, namely, the mysterious quantum critical behavior observed around <math xmlns=\\\"http://www.w3.org/1998/Math/MathML\\\"><msup><mi>x</mi><mo>*</mo></msup></math>, the so called pseudogap end point. Through a systematic variational Monte Carlo (VMC) study of the disordered 2D <math xmlns=\\\"http://www.w3.org/1998/Math/MathML\\\"><mrow><mi>t</mi><mo>−</mo><mi>J</mi></mrow></math> model from the resonating valence bond (RVB) perspective, we find that the <math xmlns=\\\"http://www.w3.org/1998/Math/MathML\\\"><mi>d</mi></math>-wave pairing in this model is remarkably more robust against the disorder effect than that in a conventional <math xmlns=\\\"http://www.w3.org/1998/Math/MathML\\\"><mi>d</mi></math>-wave BCS superconductor. We find that such remarkable robustness can be attributed to the spin-charge separation mechanism in the RVB picture, through which the <math xmlns=\\\"http://www.w3.org/1998/Math/MathML\\\"><mi>d</mi></math>-wave RVB pairing of the charge-neutral spinons becomes essentially immune to the disorder potential except for the secondary effect related to the modulation of the local doping level by the disorder. We propose that there exists a Mott transition at <math xmlns=\\\"http://www.w3.org/1998/Math/MathML\\\"><msup><mi>x</mi><mo>*</mo></msup></math>, where the RVB pairing in the underdoped regime is transmuted into the increasingly more BCS-like pairing for <math xmlns=\\\"http://www.w3.org/1998/Math/MathML\\\"><mrow><mi>x</mi><mo>></mo><msup><mi>x</mi><mo>*</mo></msup></mrow></math>, whose increasing fragility against the disorder effect leads to the non-BCS behavior and the ultimate suppression of superconductivity around <math xmlns=\\\"http://www.w3.org/1998/Math/MathML\\\"><msub><mi>x</mi><mi>c</mi></msub></math>.\",\"PeriodicalId\":20082,\"journal\":{\"name\":\"Physical Review B\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":3.7000,\"publicationDate\":\"2024-07-30\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Physical Review B\",\"FirstCategoryId\":\"101\",\"ListUrlMain\":\"https://doi.org/10.1103/physrevb.110.024521\",\"RegionNum\":2,\"RegionCategory\":\"物理与天体物理\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"Physics and Astronomy\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Physical Review B","FirstCategoryId":"101","ListUrlMain":"https://doi.org/10.1103/physrevb.110.024521","RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"Physics and Astronomy","Score":null,"Total":0}
引用次数: 0
摘要
关于杯突超导体有两个看似互不相关的谜题。第一个谜团涉及 xc 附近的强烈非 BCS 行为,xc 是过掺一侧超导穹顶的端点,据信在这里杯状超导体可以很好地用费米液体理论来描述。这一点在观察到的ρs(0)-Tc 缩放和低能量时大量未凝结的光学光谱重量中最为明显。第二个谜团是在这样一个掺杂系统中,d 波配对对不可避免的无序效应具有非凡的稳健性,这也完全出乎传统 BCS 图像的意料。在这里,我们证明这两个谜题与杯状超导体的第三个谜题--在 x* 附近观察到的神秘量子临界行为(即所谓的伪缺口端点)--的起源有着深刻的联系。通过从共振价键(RVB)的角度对无序的二维 t-J 模型进行系统的变分蒙特卡罗(VMC)研究,我们发现该模型中的 d 波配对比传统的 d 波 BCS 超导体中的 d 波配对更能抵御无序效应。我们发现,这种显著的稳健性可归因于 RVB 图景中的自旋电荷分离机制,通过这种机制,电荷中性自旋子的 d 波 RVB 配对基本上不受无序势的影响,除了与无序对局部掺杂水平的调制有关的次生效应。我们认为在 x* 处存在莫特转换,在此掺杂不足的 RVB 配对转变为 x>x* 处越来越类似 BCS 的配对,其对无序效应的脆弱性导致了非 BCS 行为,并最终抑制了 xc 附近的超导性。
Origin of the pseudogap end point in high-Tc cuprate superconductors
There are two seemingly unrelated puzzles about the cuprate superconductors. The first puzzle concerns the strong non-BCS behavior around , the end point of the superconducting dome on the overdoped side, where the cuprate is believed to be well described by the Fermi-liquid theory. This is the most evident in the observed scaling and the large amount of uncondensed optical spectral weight at low energy. The second puzzle concerns the remarkable robustness of the -wave pairing against the inevitable disorder effect in such a doped system, which is also totally unexpected from the conventional BCS picture. Here we show that these two puzzles are deeply connected to the origin of a third puzzle about the cuprate superconductors, namely, the mysterious quantum critical behavior observed around , the so called pseudogap end point. Through a systematic variational Monte Carlo (VMC) study of the disordered 2D model from the resonating valence bond (RVB) perspective, we find that the -wave pairing in this model is remarkably more robust against the disorder effect than that in a conventional -wave BCS superconductor. We find that such remarkable robustness can be attributed to the spin-charge separation mechanism in the RVB picture, through which the -wave RVB pairing of the charge-neutral spinons becomes essentially immune to the disorder potential except for the secondary effect related to the modulation of the local doping level by the disorder. We propose that there exists a Mott transition at , where the RVB pairing in the underdoped regime is transmuted into the increasingly more BCS-like pairing for , whose increasing fragility against the disorder effect leads to the non-BCS behavior and the ultimate suppression of superconductivity around .
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