Model: shreyaspullehf/superconductor-search-v2
Author: shreyaspullehf
Pipeline: sentence-similarity
Library: sentence-transformers
Tags: sentence-transformers, safetensors, bert, sentence-similarity, feature-extraction, dense, generated_from_trainer, dataset_size:4091, loss:MultipleNegativesRankingLoss, arxiv:1908.10084, arxiv:1705.00652, base_model:sentence-transformers/all-MiniLM-L6-v2, base_model:finetune:sentence-transformers/all-MiniLM-L6-v2, model-index, text-embeddings-inference, endpoints_compatible, region:us
Base models (finetune): id: sentence-transformers/all-MiniLM-L6-v2
Card metadata: tags: sentence-transformers, sentence-similarity, feature-extraction, dense, generated_from_trainer, dataset_size:4091, loss:MultipleNegativesRankingLoss
base_model: sentence-transformers/all-MiniLM-L6-v2
widget: source_sentence: magnetic order superconductor
sentences: arXiv:0802.4093v2 [cond-mat.str-el] 27 Feb 2009 Meissner eﬀect without superconductivity from a chiral d-density wave P. Kotetes∗and G. Varelogiannis† Department of Physics, National Technical University of Athens, GR-15780 Athens, Greece We demonstrate that the formation of a chiral d-density wave (CDDW) state generates a Topolo- gical Meissner eﬀect (TME) in the absence of any kind of superconductivity. The TME is identical to the usual superconducting Meissner eﬀect but it appears only for magnetic ﬁelds perpendicular to the plane while it is absent for in plane ﬁelds. The observed enhanced diamagnetic signals in the non-superconducting pseudogap regime of the cuprates may ﬁnd an alternative interpretation in terms of a TME, originating from a chiral d-density wave pseudogap. PACS numbers: 75.20.-g, 71.27.+a, 74.72.-h The Meissner eﬀect is considered to be the most direct signature of superconductivity [1]. However, the surpris- ing observations of such enhanced diamagnetic signals [2] well above the superconducting transition tempera- ture in the pseudogap regime of the cuprates [3], con- stitute a fascinating puzzle. There are two proposals for the nature of this regime that appear to dominate. The ﬁrst, associates the pseudogap with a dx2−y2 density wave (DDW) [4, 5], also called orbital antiferromagnet [6, 7], which normally competes with superconductivity. The second associates the pseudogap with spontaneous vortex-antivortex unbinding leading to incoherent super- conductivity [8] that should persist well above the su- perconducting Tc. This theory is reminiscent of the well known Kosterlitz-Thouless transition [9]. The available ARPES [10] and STM [11] experiments cannot diﬀerentiate a SC from a density wave (DW) gap, and therefore appear somehow incapable in settling di- rectly the issue. On the other hand, the unusual Nernst eﬀect and most importantly, the enhanced diamagnetic signal that accompanies it for a very large temperature region above the SC critical temperature [2], has been considered as a major argument in favor of the incoher- ent SC scenario. In fact, the enhanced diamagnetism is viewed as a signature of the usual Meissner eﬀect associ- ated solely with the SC state, and would therefore contra- dict the dx2−y2 density wave scenario since no Meissner eﬀect was expected in that case [7]. In this letter we put forward the Topological Meissner eﬀect (TME), that results from a chiral dxy + idx2−y2 density wave (CDDW) state. In fact, the Nernst region of the pseudogap regime may well be associated with a CDDW. The most intriguing property of a CDDW is that parity (P) and time-reversal (T ) violation induces Chern-Simons terms in the eﬀective action of the elec- tromagnetic ﬁeld, providing the possibility of the TME and the Spontaneous Quantum Hall eﬀect (SQHE) ear- lier discussed [12, 13, 14, 15, 16, 17, 18]. As we shall demonstrate, the TME is described by the same equa- tion we ﬁnd in the usual Meissner eﬀect of a supercon- ∗Electronic address: pkotetes@central.ntua.gr †Electronic address: varelogi@central.ntua.gr ductor. Though, its origin is radically diﬀerent. In our system we encounter the realization of Parity Anomaly [13, 19], with the emerging Chern-Simons terms provi- ding a topological mass to the electromagnetic ﬁeld, in a gauge invariant manner [20, 21]. Moreover, the pos- session of chirality perpendicular to the plane, implies that the TME is strongly anisotropic. Particularly, it takes place for magnetic ﬁelds perpendicular to the plane while it is absent for in plane ﬁelds, in accordance with the experimental observations [2]. Note ﬁnally that a chi- ral d-density wave state has also been shown recently [22] to explain the experimental results concerning the Polar Kerr eﬀect in YBCO [23]. In order to demonstrate how the TME arises, we shall consider the following BCS hamiltonian for the CDDW HCDDW = 1 2 X k  ∆kc† kck+Q + ∆∗ kc† k+Qck  , (1) which describes a dxy+idx2−y2 state characterized by the wave-vector Q = (π, π), which is commensurate to the lattice (k + 2Q = k). Since spin degrees of freedom do not get involved we have considered spinless electrons, so that all our results will refer to one spin component. Fur- thermore, we use gµν = (1, −1, −1), ki = k = (kx, ky), kµ = k = (ω, k), qµ = q = (q0, q), µ = 0, 1, 2, i = 1, 2, e > 0, ℏ= 1 and we assume that repeated indices are summed. In the derivation of the Chern-Simons terms we shall restrict ourselves to the zero temperature case while necessary extensions to ﬁnite temperatures will be afterwards performed. In addition, the summation in k−space is all over the whole 1st Brillouin zone rather than the reduced Brillouin zone. This implies that the operators ck and ck+Q do not describe independent de- grees of freedom. In Eq.(1) we have introduced the CDDW order param- eter ∆k = η∆sin kx sin ky+i∆ cos kx −cos ky  , where ∆ is the modulus of the idx2−y2 order parameter, η deﬁnes the relative magnitude of the two components and also determines the direction of the chirality of the state. The chiral character of the state implies the existence of an intrinsic angular momentum in k−space, perpendicular to the plane, originating from P −T violation. Speciﬁ- cally, the dx2−y2 component violates T as it is imaginary, 2 while the dxy component is odd under P in two dimen- sions, which is deﬁned as (kx, ky) →(kx, −ky). In order to obtain the total electronic Hamiltonian H, we have to add the corresponding kinetic part Hkin. For the kinetic part we keep only the nearest neighbors hop- ping term ǫk = −t cos kx + cos ky  satisfying the nest- ing condition ǫk+Q = −ǫk, while we also set the chem- ical potential equal to zero. Our approximation can be justiﬁed by considering that our system is close to half- ﬁlling. Under these conditions the excitation spectrum consists of two bands which are fully gapped leading to the topological quantization of the Hall conductance [12, 13, 14, 15, 16, 17, 18], which is the coeﬃcient of the Chern-Simons terms. Omitting the next nearest neigh- bors hopping term δk = t′ cos kx cos ky does not alter qualitatively the occurrence of the TME. However, its inclusion would destroy the quantization of the Hall con- ductance, as in this case, the system is not fully gapped. Similar eﬀects would arise in the presence of disorder or by including the z-axis hopping term. Under this conditions, the total Hamiltonian of the system becomes H = 1 2 P k h ǫk  c† kck −c† k+Qck+Q  +  ∆kc† kck+Q + h.c. i . We obtain a compact representa- tion of H by introducing the spinor Ψ† k = 1 √ 2(c† k c† k+Q), the isospin Pauli matrices τ and the vector gk ≡ (Re∆k, −Im∆k, ǫk). This yields H = P k Ψ† k gk · τ Ψk. The latter indicates that the ground state of the sys- tem depends on the orientation of the g vector in isospin space. As a result, this hamiltonian supports skyrmion solutions which imply the presence of a Chern-Simons action (see e.g. [18]). To reveal the emerging Chern-Simons terms, we have to take into account the ﬂuctuations of the U(1) gauge ﬁeld Aµ. We add to the Hamiltonian the term Hem = R d2q (2π)2 P k Ψ† k+qΓµ k+q,kAµ(q)Ψk − R d2q (2π)2 P k Ψ† k+q e2 2mAi(−q)Ai(q)Ψk, which describes the interaction of the gauge ﬁeld with the electrons. We have introduced the paramagnetic interaction vertex Γµ k+q,k = −(e , e ∂ ∂ki gk · τ), where µ = 0, 1, 2 and i = 1, 2. At one-loop level, the eﬀective action Sem is given by the relation Sem = 1 2 R d3q (2π)3 Aµ(−q)Πµν(q)Aν(q), with the Polarization tensor Πµν, deﬁned as Πµν(q) = i 2 R k T r  GkΓµ k,k+qGk+qΓν k+q,k  −e2 m ρeδi,j. ρe is the two- dimensional electronic density (without including spin), T r denotes trace over isospin indices, Gk is the CDDW fermionic propagator and we have used the abbreviation R k = R dω 2π P k. Computing Πµν up to linear order in q, yields the Chern-Simons action SCS = Z d3x σxy 4 εµνλAµF νλ, (2) with Fµν = ∂µAν −∂νAµ. The coeﬃcient of the Chern- Simons action is the Hall conductance σxy. It can be shown that it is a topological invariant, reﬂecting the existence of a topologically non trivial, P −T violating ground state (see e.g. [18]). Using Eq.(2) we obtain σxy = i 2!ε0ji ∂Π0i ∂qj = e2 4π b N = e2 2π , (3) where we have introduced the winding number of the unit vector ˆgk = gk/| gk |, b N = 1 4π Z d2k ˆgk · ∂ˆgk ∂kx × ∂ˆgk ∂ky ! , (4) which is equal to 2, because the order parameter com- ponents are eigenfunctions of the angular momentum in k−space with eigenvalue l = 2. In the case of a perfect gap, the Hall conductance origi- nates only from the chirality b N of the lower energy band, E− k = −|gk|, which is fully occupied. In the same time, the upper band, E+ k = +|gk|, is totally empty while it is characterized by opposite chirality. Apparently, if both bands were equally occupied then σxy would be equal to zero. In the general case, the two bands, have diﬀerent occupation numbers n−and n+, yielding a non-quantized Hall conductance σxy = e2 2π(n−−n+). Deviations from nesting, disorder or a chemical potential generally lead to such an eﬀect. It is desirable to comprehend, even crudely, the eﬀect of these parameters on the Hall con- ductance and the TME. For this purpose we consider that a ﬁnite chemical po- tential is added to the system. We shall consider that its magnitude is of the order of min|gk|. This minimum is realized at the points k0 = (± π 2 , ± π 2 ), when η << 1. In this case, we may linearize the spectrum about these points so to obtain an approximate analytical solution. The two energy bands are described by the dispersions E± k = −µ± p m2 + (v0 · δk)2, with m = min|gk| = |gk0|, v0 the velocity at these points and δk = k−k0. If |µ| ≥m and µ < 0, hole-pockets arise in the lower band decreas- ing the full occupancy from n−= 1 to n−= 1−nex, with nex the portion of the empty states. On the other hand, if µ ≥m, electron pockets emerge in the upper band ris- ing its occupancy from zero. However, if we take into consideration that the two bands have opposite chirality, it is evident that in both cases, the eﬀect is the same. Consequently, σxy(µ) = σxy(1 −nex). The portion of the empty states will be determined by the area of the el- lipses deﬁned by the four hole-pockets. Straightforward calculations yield the simple relation nex = (µ2 −m2)/2πt∆. (5) We observe that for small values of |µ|, compared to t and ∆, the eﬀect of doping is negligible. We are now in position to obtain the equations of mo- tion of the gauge ﬁeld which will allow us to discuss the TME in a Hall bar geometry setup. We consider that the 3 FIG. 1: (Color online) (a) Inﬂuence of doping on the Topo- logical Meissner eﬀect. The relative change of magnetization hardly reaches 1% in the presence of a small chemical po- tential (∆= 20meV , t = 500meV ). (b) The magnetic ﬁeld screening as a function of the position on the Hall bar extend- ing from −lx to +lx, for diﬀerent values of the penetration depth λ over lx. The magnetic ﬁeld is totally expelled from the sample when lx/λ >> 1 exactly as in the superconducting case. Hall bar has dimensions Lx = 2lx, Ly >> Lx extending from −lx to lx on the x-axis. The relation Ly >> Lx in- dicates that there is negligible y-dependence of the, QCage - A New Microwave-cavity Sample Holder for High-fidelity Qubit Measurements | In this video, you will learn about a new sample holder system, targeted at superconducting quantum processors with tens of qubits.

The QCage is a sample holder system for microwave resonator-based quantum devices that encloses the sample chip in an all-surrounding microwave cavity, with a total number of 24 coplanar transmission lines optimized for frequencies up to 18 GHz. The QCage is designed to hold the chip suspended inside the cavity, supported only by four corner pedestals and clamped d, Elastic neutron scattering simultaneously probes both the crystal structure
and magnetic order in a material. Inelastic neutron scattering measures phonons
and magnetic excitations. Here, we review the average composition, crystal
structure and magnetic order in the 245 family of Fe-based superconductors and
in related insulating compounds from neutron diffraction works. A
three-dimensional phase-diagram summarizes various structural, magnetic and
electronic properties as a function of the sample composition. A high pressure
phase diagram for the superconductor is also provided. Magnetic excitations and
the theoretic Heisenberg Hamiltonian are provided for the superconductor.
Issues for future works are discussed., source_sentence: superconductivity
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Bechgaard, J. de Phys. (Paris) Lett. 43, L565 (1982). 185. H. Schwenk, K. Andres, and F. Wudl, Phys. Rev. B 29, 500 (1984). 186. W. Wu et al., Phys. Rev. Lett. 94, 097004 (2005). 187. W. Kohn and J. M. Luttinger, Phys. Rev. Lett. 15, 524 (1965). 188. V. J. Emery, Synthetic Metals 13, 21 (1986). 189. M. T. B´eal-Monod, C. Bourbonnais, and V. J. Emery, Phys. Rev. B 34, 7716 (1986). 190. L. G. Caron and C. Bourbonnais, Physica 143B, 453 (1986). 191. D. J. Scalapino, E. Loh, and J. E. Hirsch, Phys. Rev. B 34,, By periodically driving a single bosonic Josephson junction (BJJ) with an
impurity, a synthetic gauge field is generated in the Fock space of the system.
At a critical synthetic gauge flux the ground state undergoes a quantum phase
transition which is analogous to the Meissner-Abrikosov-vortex transition found
in type-II superconductors with an applied magnetic field. A second quantum
phase transition involving attractive interactions between the bosons of the
BJJ is shown to enhance the sensitivity of the system to the
Meissner-Abrikosov-vortex transition., source_sentence: superconductivity
sentences: Room-Temperature Superconductor LK-99 Revolutionary Science | Room-Temperature Superconductor LK-99 Revolutionary Science.
Dive deep into the groundbreaking discovery of LK-99, a room-temperature superconductor that's challenging our understanding of physics. From its origins to its potential applications, we explore how this scientific marvel could reshape industries and redefine the future of technology. Join us as we unravel the mysteries of superconductivity, the controversies surrounding it, and the potential it holds for a brighter, more efficient fu, 3. Results
In the following calculations, we set ∆= 1 meV as the en-
ergy unit. The superconducting coherence length is ξ = ℏvF/∆≈
360 nm, which is set as the length unit.
3.1. Josephson junction with out-of-plane spin polarization
The Josephson junction with the out-of-plane spin polariza-
tion is schematically shown in Fig. 1(a), where the spin polar-
ization in the left superconducting region is along the z axis and
the spin polarization in the right superconducting region lies in
the y −z plane with the polar angle θm. The Andreev-like trans-
fer matrices at the NS interfaces are given by
Sν =
1
cos θν cos ϕν + i sin ϕν
×
 sin θν cos ϕν + cos γ
−i sin γ
i sin γ
sin θν cos ϕν −cos γ
!
,
(13)
where ν = + (−) for the right (left) interface, θ+ = θm, θ−= 0,
and ϕ± = ±ϕs/2. The Andreev-like bound states can be found
from the same determinant in Eq. (12), which are given by
det

1 −M−1S−1
+ MS−

= 0,
(14)
leading to the Andreev-like levels

E±
∆
 =
s
Y2 −2XZ ±
p
Y2 −4Y2Z (X + Z)
2 X2 + Y2
,
(15)
X = 2 sin2 α −(3 + cos 2α) cos(2kL),
Y = −4 cos α sin(2kL),
Z = cos2 α cos ϕs + cos θm cos ϕs
+ cos θm + 2 cos(2kL) −1.
With the help of Eq. (12), the spin Josephson current density
at T = 0 K can be obtained by the ϕs-dependent Andreev-like
levels
j(ϕs) = −
X
ℓ=±
Z
µW
2πℏvF
dEℓ
dϕs
cos αdα,
(16)
where Eℓis the positive root of Eq. (15) and W is the width of
the junction.
The supercurrent-phase relations at different θm are shown
in Fig. 2(a) for kFL = 0.1. The spin Josephson current de-
creases with the increasing of θm, and drops to zero when the
spin polarizations in the left and right superconducting regions
are antiparallel, i.e., θm = π. In this antiparallel configuration,
the spin polarizations of the spin-triplet electron-hole condensa-
tions in the left and right spin superconductors are opposite, the
Andreev-like process between two NS interfaces can not form
a closed loop. Consequently, the ϕs-dependent Andreev-like
levels are abesnt, leading to the zero supercurrent.
For kFL = 2, the supercurrent is reversed and the π-state
Josephson junction appears, as shown in Fig. 2(b). This 0 −π
phase transition is attributed to the Fermi-momentum splitting
Andreev-like reflections at the NS interfaces. At the Fermi sur-
face, the right-propagating spin-up electron with the wave vec-
tor kF is converted into a left-propagating spin-down electron
with the wave vector −kF due to the Andreev-like reflection,
leading to the wave vector difference ∆k = 2kF. An additional
phase shift 2kFL is accumulated in a closed Andreev loop. The
total scattering phase acquired by the electrons in this closed
Andreev loop is 2kFL ± ϕs −2 arccos(E/∆) [26], which should
3
−2
0
−3
0
3
2
kF L = 0.1
ϕm = 0
π
φs/π
j/j0
(a)
−2
0
−3
0
3
2
kF L = 2
ϕm = 0
π
φs/π
j/j0
(b)
0
5
10
15
0
1
2
L/ξ
jc/j0
(c)
ϕm = 0.3π
ϕm = 0.8π
−1
0
0
1
2
1
ϕm/π
jc/j0
(d)
L = 0.1ξ
L = 1.5ξ
Figure 3: (a, b) The current-phase relation for the Josephson junctions with the in-plane spin polarization. The red arrows indicate the curves with the increasing
deviation of the relative angles φm, which change from 0 to π with a step of π/4. (c) The critical spin Josephson current density jc as a function of L for φm = 0.3π
(solid) and φm = 0.8π (dashed). The Fermi level is µ = 0.5∆. (d) The critical spin Josephson current density jc as a function of θm for L = 0.1ξ (solid) and L = 1.5ξ
(dashed). Both j and jc are renormalized by j0 = µ∆W/2πℏvF.
be quantized according to the quasiclassical Bohr-Sommerfeld
quantization condition [27, 28], i.e., 2kFL±ϕs−2 arccos(E/∆) =
2πn (n ∈Z). Consequently, the state of the junction can be con-
trolled by the phase factor cos(kFL). The spin supercurrent can
be expressed as j ∝cos(kFL) sin ϕs. For 2nπ + π/2 < kFL <
2nπ + 3π/2, the spin supercurrent is reversed.
The critical current defined by jc = max | j(ϕs)| as a function
of the junction length L is shown in Fig. 2(c). Due to the addi-
tional phase kFL, the critical current is proportional to cos(kFL),
which exhibits an oscillation behavior as the the junction length
increases. For µ = 0.5∆in Fig. 2(c), the oscillation period can
be estimated as TL = π/kF = 2πξ. The critical current as a
function of the polar angle θm is shown in Fig. 2(d). The θm-
dependent critical current is symmetric due to the rotation sym-
metry, i.e., jc(θm) = jc(−θm). The critical current reaches its
maximum value at θm = 0 and becomes zero at θm = ±π.
3.2. Josephson junction with in-plane spin polarization
The Josephson junction with in-plane spin polarization is
schematically shown in Fig. 1(b), where the spin polarization in
the left superconducting region is along the x axis and the spin
polarization in the right superconducting region lies in the x −y
plane with the azimuthal angle φm. The Andreev-like transfer
matrices are given by
Sν =
−ieiφν
sin(φν + ϕν)×
 cos (φν + ϕν) + cos γ
−i sin γ
i sin γ
cos (φν + ϕν) −cos γ
!
,
(17)
where ν = + (−) for the right (left) interface, φ+ = φm, φ−= 0,
and ϕ± = ±ϕs/2. The Andreev-like levels are given by

E±
∆
 =
v
u
u
u
u
t ¯Y2 −2 ¯X ¯Z ±
q
¯Y2 −4 ¯Y2 ¯Z
 ¯X + ¯Z

2
 ¯X2 + ¯Y2
,
(18)
¯X = 8(3 cos(2kL) + 2 cos 2α cos2(kL) −1),
¯Y = 32 cos α sin(2kL),
¯Z = −4 cos2 α2 cos φm −cos 2φm + cos ϕs
+2 cos(φm + ϕs) + cos(2φm + ϕs) + 4 cos(2kL) −1.
The zero-temperature Josephson current obtained by Eq.
(16) is shown in Fig. 3(a) at kFL = 0.1. Due to the spin ro-
tation symmetry, the supercurrent for the Josephson junctions
with parallel in-plane spin polarization (φm = 0) is the same as
that for the Josephson junctions with parallel out-of-plane spin
polarization (θm = 0). For the antiparallel in-plane polarization
(φm = π), the Josephson current is absent due to the absence of
the ϕs-dependent Andreev-like levels.
For φm , 0 and φm , π, the anomalous Josephson current
j|ϕs=0 appears, as shown in Fig. 3(a). For simplicity, we present
the spin Josephson current for the one-dimensional (1D) case
with ky = 0:
j1D ∝cos (kFL) cos2 φm
2

sin (ϕs + φm) ,
(19)
which can imply the qualitative properties of the two-dimensional
Josephson junctions. Eq. (19) shows that the anomalous Joseph-
son current at ϕs = 0 is proportional to cos(kFL) cos2(φm/2) sin φm.
The Josephson current can be reversed by the additional phase
factor cos(kFL). For kFL = 2, the reversed Josephson current
obtained from Eq. (16) is shown in Fig. 3(b).
The critical currents jc as a function of the junction length
L and the azimuthal angle φm are shown in Figs. 3(c) and 3(d),
respectively. The L-dependent oscillation is determined by the
additional phase factor cos(kFL) due to the Fermi-moment split-
ting. For a fixed L, the φm-resolved jc is symmetric, as shown
in Fig. 3(d).
4
The anomalous Josephson current j|ϕs=0 as a function of L
is shown in Fig. 4(a). For φm = 0 and φm = π, the anomalous
Josephson effect is absent. For φm , 0 and φm , π, j|ϕs=0
oscillates with the increasing of L and has the same oscillation
period as jc. For µ = ∆in Fig. 4(a), the oscillation period is
about πξ. j|ϕs=0 as a function of φm is shown in Fig. 4(b). The
φm-resolved anomalous Josephson current is asymmetric and
satisfies the relation
j|ϕs=0(φm) = −j|ϕs=0(−φm),
(20)
due to the symmetry of the BdG Hamiltonian, which is ex-
plained in detail in Sec. 3.3.
3.3. Symmetry analysis
The Hamiltonian of the spin superconductor with out-of-
plane spin polarization can be written as
Hη
S = hη(k) + H′(ϕs, θm),
(21)
where η = ± is the valley index, the k-dependent term hη(k) =
ℏvF(kxτx + ηkyτy) is the Hamiltonian of the pristine graphene
for the η valley and the k-independent term is given by
H′(ϕs, θm) =M cos θmσzτ0 + M sin θmσxτ0
+ ∆cos θm cos ϕsσxτz + ∆sin θm cos ϕsσzτz
−∆sin ϕsσyτz.
(22)
Under the time-reversal transformation, the Hamiltonian of the
pristine graphene remains unchanged
hη(k) →T h¯η(−k)T −1
= ℏvF(kxτx + ηkyτy)
= hη(k),
(23)
where ¯η = −η, T = iσyτzC is the time-reversal operator with C
being the complex conjugation. For the k-independent Hamilto-
nian H′(ϕs, θm), considering the combined symmetry P = σyT
with σy being the spin rotation symmetry and T being the time-
reversal symmetry, one finds that
PH′(ϕs, θm)P−1 = H′(−ϕs, θm).
(24)
0
5
10
15
−1
0
1
L/ξ
j|φs=0/j0
(a)
ϕm = 0.5π
ϕm = 0, π
−1
0
−1
0
1
1
ϕm/π
j|φs=0/j0
(b)
L = 0.1ξ
L = 1.5ξ
Figure 4: (a) The anomalous spin Josephson current density j|ϕs=0 as a function
of L for φm = 0.5π (solid) and φm = 0, π (dashed). The Fermi level is µ = ∆. (b)
The anomalous spin Josephson current j|ϕs=0 as a function of φm for Lm = 0.1ξ
(solid) and L = 1.5ξ (dashed). j|ϕs=0 is renormalized by j0 = µ∆W/2πℏvF.
Due to the spin degeneracy in pristine graphene, hη(k) remains
unchanged under P. Consequently, with the help of Eq. (6), the
BdG Hamiltonian for the Josephson junctions with the out-of-
plane spin polarization holds the relation
PHBdG(ϕs, θm)P−1 = HBdG(−ϕs, θm).
(25)
The spin Josephson current density can be obtained via the ther-
modynamic relation [29, 30]
j(ϕs) = −kBT∂ϕs ln Tr[e−HBdG(ϕs)/kBT].
(26)
By substituting Eq. (25) into Eq. (26), one finds that the spin
Josephson current holds the relation
j(ϕs, θm) = −j(−ϕs, θm).
(27)
leading to the absence of the anomalous spin Josephson current,
i.e., j|ϕs=0 = 0.
For the spin superconductor with in-plane spin polarization,
the Hamiltonian can be written as
Hη
S = hη(k) + H′′(ϕs, φm),
(28)
with
H′′(ϕs, φm) =M cos φmσxτ0 + M sin φmσyτ0
−∆sin(φm + ϕs) cos φmσyτz
+ ∆sin(φm + ϕs) sin φmσxτz
−∆cos(φm + ϕs)σzτz.
(29)
The symmetry P is broken and the BdG Hamiltonian holds the
relation
PHBdG(ϕs, φm)P−1 = HBdG(−ϕs, −φm).
(30)
With the help of Eq. (26), one finds that the spin Josephson
current holds the relation
j(ϕs, φm) = −j(−ϕs, −φm),
(31)
leading to the presence of the anomalous spin Josephson cur-
rent. The anomalous Josephson current is an odd function of φm
satisfying j|ϕs=0(φm) = −j|ϕs=0(−φm), as shown in Fig. (4)(b).
In fact, the anomalous Josephson effect is possible when
the symmetries T , D and P are all broken [31, 32], where
D = σyRxzT is another combined symmetry with Rxz being the
mirror reflection about the x −z plane. We note that the sym-
metries T and D are always broken in our model for both the
out-of-plane spin polarization and the in-plane spin polariza-
tion. The combined symmetry P plays a key role in our model:
For the Josephson junction with out-of-plane spin polarization,
the absence of the anomalous Josephson current ( j|ϕs=0 = 0)
is protected by P. For the Josephson junction with in-plane
spin polarization, the breaking of P leads to the presence of the
anomalous spin Josephson current.
5, A brief course on Superconductivity [Introduction Video] | Course Name: A brief course on Superconductivity

Prof. Saurabh Basu
Department of Physics
Indian Institute of Technology Guwahati, source_sentence: how operate
sentences: The recently discovered universal scaling relation between the
superconducting density and the transition temperature in high-temperature
superconductors appears to indicate that those normal state carriers that are
undergoing a superconducting transition at T = Tc, are experiencing critical
dissipation and acting as preformed pairs., The discovery of nickelate superconductivity provided the first example of a
non-copper-based material with superconductivity strongly analogous to the
cuprates, but recent findings raise questions and inconsistencies around the
electron counts and doping phase diagrams. We show using superconducting
La$_4$Ni$_3$O$_{10}$ that there are unconventional interlayer and interorbital
intrinsic doping effects that render the $d_{x^2-y^2}$ orbital occupation
similar to the cuprates. The results enable a consistent framework for
nickelate superconductivity, while maintaining the connection between cuprate
and nickelate superconductors., How To: Operate Jeep JL Wrangler Four Wheel Drive 4wd 4x4 Command Trac Rock Trac| Kentucky Ohio IN | Easy operation for JL Jeep Wrangler Four Wheel Drive System 4wd 4x4. Need to know how to operate your Jeep's Four Wheel Drive System? 2018 Jeep JL Wrangler Unlimited 4 Door Sport, Rubicon, Sahara, Moab Edition, Gladiator. 4 Wheel High. Watch this video in Louisville Kentucky. We are close to Ohio, Indiana, St Louis, Indianapolis, Nashville, Tennessee, West Virginia, Missouri. Aev Dealer. American Expedition Vehicles. Montana. Detroit. New Albany. Dana 44. 
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htt, source_sentence: superconductivity
sentences: Quantum Levitation With YBCO SUPERCONDUCTOR! | Patreon: https://www.patreon.com/Thoisoi?ty=h
Facebook: https://www.facebook.com/thoisoi2
Music: http://audiomicro.com
Hello everyone. Today I want to tell you about one unusual subject - the superconductor.
A superconductor or a high-temperature superconducting ceramics is an alloy of oxides of yttrium, barium and copper in proportions (which you see on the screen) YBa2Cu3O7-x and abbreviated as YBCO.
The ceramics was first made in the University of Alabama, USA in 1987. The uniqueness of this , Non-invasive magnetic field sensing using optically - detected magnetic
resonance of nitrogen-vacancy (NV) centers in diamond was used to study spatial
distribution of the magnetic induction upon penetration and expulsion of weak
magnetic fields in several representative superconductors. Vector magnetic
fields were measured on the surface of conventional, Pb and Nb, and
unconventional, LuNi$_2$B$_2$C, Ba$_{0.6}$K$_{0.4}$Fe$_2$As$_2$,
Ba(Fe$_{0.93}$Co$_{0.07}$)$_2$As$_2$, and CaKFe$_4$As$_4$, superconductors,
with diffraction - limited spatial resolution using variable - temperature
confocal system. Magnetic induction profiles across the crystal edges were
measured in zero-field-cooled (ZFC) and field-cooled (FC) conditions. While all
superconductors show nearly perfect screening of magnetic fields applied after
cooling to temperatures well below the superconducting transition, $T_c$, a
range of very different behaviors was observed for Meissner expulsion upon
cooling in static magnetic field from above $T_c$. Substantial conventional
Meissner expulsion is found in LuNi$_2$B$_2$C, paramagnetic Meissner effect
(PME) is found in Nb, and virtually no expulsion is observed in iron-based
superconductors. In all cases, good correlation with macroscopic measurements
of total magnetic moment is found. Our measurements of the spatial distribution
of magnetic induction provide insight into microscopic physics of the Meissner
effect., We highlight the reproducibility and level of control over the electrical
properties of YBa$_2$Cu$_3$O$_7$ Josephson junctions fabricated with
irradiation from a focused helium ion beam. Specifically, we show the results
of electrical transport properties for several junctions fabricated using a
large range of irradiation doses. At the lower end of this range, junctions
exhibit superconductor-normal metal-superconductor (SNS) Josephson junction
properties. However, as dose increases there is a transition to electrical
characteristics consistent with superconductor-insulator-superconductor (SIS)
junctions. To investigate the uniformity of large numbers of helium ion
Josephson junctions we fabricate arrays of both SNS and SIS Josephson junctions
containing 20 connected in series. Electrical transport properties for these
arrays reveal very uniform junctions with no appreciable spread in critical
current or resistance.
pipeline_tag: sentence-similarity
library_name: sentence-transformers
metrics: cosine_accuracy@1, cosine_accuracy@3, cosine_accuracy@5, cosine_accuracy@10, cosine_precision@1, cosine_precision@3, cosine_precision@5, cosine_precision@10, cosine_recall@1, cosine_recall@3, cosine_recall@5, cosine_recall@10, cosine_ndcg@10, cosine_mrr@10, cosine_map@100
model-index: name: SentenceTransformer based on sentence-transformers/all-MiniLM-L6-v2
results: task: type: information-retrieval
name: Information Retrieval
dataset: name: superconductor eval
type: superconductor-eval
metrics: type: cosine_accuracy@1
value: 0.7
name: Cosine Accuracy@1
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value: 0.7861111111111111
name: Cosine Mrr@10
verified: no, type: cosine_map@100
value: 0.7098290598290597
name: Cosine Map@100
verified: no
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