Youichi Yamakawa
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View article: Quantum metric–induced giant and reversible nonreciprocal transport phenomena in chiral loop-current phases of kagome metals
Quantum metric–induced giant and reversible nonreciprocal transport phenomena in chiral loop-current phases of kagome metals Open
Emergence of quantum orders with nontrivial quantum geometric properties in metals represent central issues in condensed matter physics. In this context, recently discovered chiral loop-current order in kagome metals has garnered significa…
View article: Impact of charge-density-wave pattern on the superconducting gap in Vanadium-based kagome superconductors
Impact of charge-density-wave pattern on the superconducting gap in Vanadium-based kagome superconductors Open
Kagome metals $A$V$_3$Sb$_5$ ($A=$ K, Rb, Cs) provide a compelling platform to explore the interplay between superconductivity (SC) and charge-density-wave (CDW) orders. While distinct CDW orders have been identified in K/RbV$_3$Sb$_5$ ver…
View article: Paramagnon-Interference Mechanism for Three-Dimensional Bond Order in Kagome Metals AV$_3$Sb$_5$ (A=Cs, Rb, K): Analysis by the Density-Wave Equation
Paramagnon-Interference Mechanism for Three-Dimensional Bond Order in Kagome Metals AV$_3$Sb$_5$ (A=Cs, Rb, K): Analysis by the Density-Wave Equation Open
The mechanism of CDW and its 3D structure are important fundamental issues in kagome metals. We have previously shown that, based on a 2D model, $2\times 2$ bond order (BO) emerges due to the paramagnon-interference (PMI) mechanism and tha…
View article: Quantum-metric-induced giant and reversible nonreciprocal transport phenomena in chiral loop-current phases of kagome metals
Quantum-metric-induced giant and reversible nonreciprocal transport phenomena in chiral loop-current phases of kagome metals Open
Rich spontaneous symmetry-breaking phenomena with nontrivial quantum geometric properties in metals represent central issues in condensed matter physics. In this context, the emergence of chiral loop-current order, accompanied by time-reve…
View article: Giant Impurity Effects on Charge Loop Current Order States in Kagome Metals
Giant Impurity Effects on Charge Loop Current Order States in Kagome Metals Open
The exotic electronic states in the charge loop current (cLC) phase, in which the permanent charge current breaks the time-reversal symmetry, have been attracting increasing attention in recently discovered kagome metals AV3Sb5 (A = Cs, Rb…
View article: Drastic magnetic-field-induced chiral current order and emergent current-bond-field interplay in kagome metals
Drastic magnetic-field-induced chiral current order and emergent current-bond-field interplay in kagome metals Open
In kagome metals, the chiral current order parameter with time-reversal-symmetry-breaking is the source of various exotic electronic states, while the method of controlling the current order and its interplay with the star-of-David bond…
View article: Superconductivity in Ternary Zirconium Telluride Zr6MTe2 with 3d Transition Metals
Superconductivity in Ternary Zirconium Telluride Zr6MTe2 with 3d Transition Metals Open
We report the synthesis, electronic properties, and electronic states of Zr6MTe2 (M = Cr, Mn, Fe, and Co), which is isostructural to a recently discovered superconductor family Sc6MTe2. Based on the electrical resistivity and heat capacity…
View article: Real-space Loop Current Pattern in Time-reversal-symmetry Breaking Phase in Kagome Metals
Real-space Loop Current Pattern in Time-reversal-symmetry Breaking Phase in Kagome Metals Open
The charge loop current (cLC) state has attracted increasing attention in kagome metals. Here, we calculate the spontaneous currents along the nearest sites $i$ and $j$, $J_{i,j}$, induced by the cLC order that is the imaginary and odd-par…
View article: Superconductivity in Ternary Germanide ScPdGe and Silicide ScPdSi
Superconductivity in Ternary Germanide ScPdGe and Silicide ScPdSi Open
The electronic properties of ScPdGe and ScPdSi, crystallizing in the hexagonal ZrNiAl and orthorhombic TiNiSi structures, respectively, are investigated. ScPdGe and ScPdSi are found to show bulk superconductivity below 0.9 and 1.7 K, respe…
View article: Charge-loop current order and Z3 nematicity mediated by bond order fluctuations in kagome metals
Charge-loop current order and Z3 nematicity mediated by bond order fluctuations in kagome metals Open
Recent experiments on geometrically frustrated kagome metal A V 3 Sb 5 ( A = K, Rb, Cs) have revealed the emergence of the charge loop current (cLC) order near the bond order (BO) phase. However, the origin of the cLC and its interplay wit…
View article: Superconductivity in Ternary Scandium Telluride Sc<sub>6</sub><i>M</i>Te<sub>2</sub> with 3<i>d</i>, 4<i>d</i>, and 5<i>d</i> Transition Metals
Superconductivity in Ternary Scandium Telluride Sc<sub>6</sub><i>M</i>Te<sub>2</sub> with 3<i>d</i>, 4<i>d</i>, and 5<i>d</i> Transition Metals Open
We report the discovery of bulk superconductivity in Sc6MTe2 with seven kinds of transition-metal elements M. The critical temperatures for M = 3d elements are higher than those for 4d and 5d elements and increase in the order of M = Ni, C…
View article: Low temperature phase transitions under CDW state in kagome metals AV3Sb5 (A=Cs,Rb,K): Significance of mix-type Fermi surface electron correlations
Low temperature phase transitions under CDW state in kagome metals AV3Sb5 (A=Cs,Rb,K): Significance of mix-type Fermi surface electron correlations Open
To understand the multistage phase transitions in V-based kagome metals inside the charge-density-wave (CDW) phase, we focus on the impact of the "mix-type" Fermi surface because it is intact in the CDW state on the "pure-type" Fermi surfa…
View article: Odd-parity quadrupole order and induced nonreciprocal transport in the kagome metal CsTi$_3$Bi$_5$ driven by quantum interference
Odd-parity quadrupole order and induced nonreciprocal transport in the kagome metal CsTi$_3$Bi$_5$ driven by quantum interference Open
Kagome metals present a fascinating platform of quantum phases thanks to the interplay between the geometric frustration and strong electron correlation. Here, we propose the emergence of the electric odd-parity bond order (BO) that origin…
View article: Superconductivity in Ternary Scandium Telluride Sc6MTe2 with 3d, 4d, and 5d Transition Metals
Superconductivity in Ternary Scandium Telluride Sc6MTe2 with 3d, 4d, and 5d Transition Metals Open
We report the discovery of bulk superconductivity in Sc6MTe2 with seven kinds of transition-metal elements M. The critical temperatures for M = 3d elements are higher than those for 4d and 5d elements and increase in the order of M = Ni, C…
View article: Drastic magnetic-field-induced chiral current order and emergent current-bond-field interplay in kagome metals
Drastic magnetic-field-induced chiral current order and emergent current-bond-field interplay in kagome metals Open
In kagome metals, the chiral current order $η$ with time-reversal-symmetry-breaking is the source of various exotic electronic states, while the method of controlling the current order and its interplay with the star-of-David bond order $ϕ…
View article: Rigorous formalism for unconventional symmetry breaking in Fermi liquid theory and its application to nematicity in FeSe
Rigorous formalism for unconventional symmetry breaking in Fermi liquid theory and its application to nematicity in FeSe Open
Unconventional symmetry breaking due to nonlocal order parameters has attracted considerable attention in many strongly correlated metals. Famous examples are the nematic order in Fe-based superconductors and the star-of-David charge densi…
View article: Charge-loop current order and Z<sub>3</sub>-nematicity mediated by bond-order fluctuations in kagome metals
Charge-loop current order and Z<sub>3</sub>-nematicity mediated by bond-order fluctuations in kagome metals Open
Numerical data of "Charge-loop current order and $Z_3$-nematicity mediated by bond-order fluctuations in kagome metals"
View article: Correlation-driven electronic nematicity in the Dirac semimetal BaNiS <sub>2</sub>
Correlation-driven electronic nematicity in the Dirac semimetal BaNiS <sub>2</sub> Open
In BaNiS 2 , a Dirac nodal line band structure exists within a two-dimensional Ni square lattice system, in which significant electronic correlation effects are anticipated. Using scanning tunneling microscopy (STM), we discover signs of c…
View article: Unconventional density waves and superconductivities in Fe-based superconductors and other strongly correlated electron systems
Unconventional density waves and superconductivities in Fe-based superconductors and other strongly correlated electron systems Open
To seek high-$T_c$ pairing mechanism, many scientists have focused on the mysterious spontaneous rotational symmetry breaking above Tc, such as nematic order at $q=0$ and smectic order at $q\ne0$. Such exotic correlation-driven symmetry br…
View article: Charge-loop current order and Z3 nematicity mediated by bond-order fluctuations in kagome metal AV3Sb5 (A=Cs,Rb,K)
Charge-loop current order and Z3 nematicity mediated by bond-order fluctuations in kagome metal AV3Sb5 (A=Cs,Rb,K) Open
Recent experiments on geometrically frustrated kagome metal AV3Sb5 (A=K, Rb, Cs) have revealed the emergence of the charge loop current (cLC) order near the bond order (BO) phase. However, the origin of the cLC and its relation to other ph…
View article: Mechanism of exotic density-wave and beyond-Migdal unconventional superconductivity in kagome metal AV <sub>3</sub> Sb <sub>5</sub> (A = K, Rb, Cs)
Mechanism of exotic density-wave and beyond-Migdal unconventional superconductivity in kagome metal AV <sub>3</sub> Sb <sub>5</sub> (A = K, Rb, Cs) Open
Exotic quantum phase transitions in metals, such as the electronic nematic state, have been discovered one after another and found to be universal now. The emergence of unconventional density-wave (DW) order in frustrated kagome metal AV 3…
View article: <i>d</i>- and <i>p</i>-wave Quantum Liquid Crystal Orders in Cuprate Superconductors, <i>κ</i>-(BEDT-TTF)<sub>2</sub>X, and Coupled Chain Hubbard Models: Functional-renormalization-group Analysis
<i>d</i>- and <i>p</i>-wave Quantum Liquid Crystal Orders in Cuprate Superconductors, <i>κ</i>-(BEDT-TTF)<sub>2</sub>X, and Coupled Chain Hubbard Models: Functional-renormalization-group Analysis Open
Unconventional symmetry breaking without spin order,such as the rotational symmetry breaking (=nematic or smectic) orders as well as the spontaneous loop-current orders, have been recently reported in cuprate superconductors and their rela…
View article: $d$- and $p$-wave quantum liquid crystal orders in cuprate superconductors, $\kappa$-(BEDT-TTF)$_2$X, and coupled chain Hubbard models: functional-renormalization-group analysis
$d$- and $p$-wave quantum liquid crystal orders in cuprate superconductors, $\kappa$-(BEDT-TTF)$_2$X, and coupled chain Hubbard models: functional-renormalization-group analysis Open
Unconventional symmetry breaking without spin order,such as the rotational symmetry breaking (=nematic or smectic) orders as well as the spontaneous loop-current orders, have been recently reported in cuprate superconductors and their rela…
View article: Emergence of charge loop current in the geometrically frustrated Hubbard model: A functional renormalization group study
Emergence of charge loop current in the geometrically frustrated Hubbard model: A functional renormalization group study Open
Spontaneous current orders due to odd-parity order parameters attract increasing attention in various strongly correlated metals. Here, we discover a novel spin-fluctuation-driven charge loop current (cLC) mechanism based on the functional…
View article: Prediction of $d$-wave bond-order and pseudogap in organic superconductor $\kappa$-(BEDT-TTF)$_2$X: Similarities to cuprate superconductors
Prediction of $d$-wave bond-order and pseudogap in organic superconductor $\kappa$-(BEDT-TTF)$_2$X: Similarities to cuprate superconductors Open
Rich pseudogap phenomena due to unconventional orders, such as the inter-site order parameter called the bond-order (BO), attract increasing attention in condensed matter physics. Here, we investigate the occurrence of the unconventional o…
View article: High-mobility carriers induced by chemical doping in the candidate nodal-line semimetal CaAgP
High-mobility carriers induced by chemical doping in the candidate nodal-line semimetal CaAgP Open
We report the electronic properties of single crystals of candidate\nnodal-line semimetal CaAgP. The transport properties of CaAgP are understood\nwithin the framework of a hole-doped nodal-line semimetal. In contrast,\nPd-doped CaAgP show…
View article: Doping effects on electronic states in electron-doped FeSe: Impact of self-energy and vertex corrections
Doping effects on electronic states in electron-doped FeSe: Impact of self-energy and vertex corrections Open
The pairing glue of high-$T_{\rm c}$ superconductivity in heavily electron-doped (e-doped) FeSe, in which hole-pockets are absent, has been an important unsolved problem. Here, we focus on a heavily e-doped bulk superconductor Li$_{1-x}$Fe…
View article: Spontaneous spin-loop-current order mediated by transverse spin fluctuations in cuprate superconductors
Spontaneous spin-loop-current order mediated by transverse spin fluctuations in cuprate superconductors Open
We predict the theoretical occurrence of nanoscale spontaneous spin-current, called the spin loop-current (sLC) order, as a promising origin of the pseudogap and electronic nematicity in cuprates. We demonstrate that the spontaneous sLC is…