Unlike an ordinary metallic conductor, whose resistance decreases gradually as its temperature is lowered even. The electrons within a cdw form a standing wave pattern and sometimes collectively carry an electric current. We describe the interplay between dwave superconductivity and spin density wave sdw order in a theory of the holedoped cuprates at hole. The relationship between the spin density wave sdw and superconductivity is a central topic in the research on the feasbased high tc superconductors. In the ideal case, when the pinning and the damping of the fisdw can be neglected, it is found that the counterflow of the fisdw precisely cancels the quantum hall current, so that the resultant hall conductivity is zero. Symmetrybreaking orbital anisotropy observed for detwinned. Pfuner et al charge dynamics of the spindensitywave state in bafe2as2 515 modes are screened by the e. Tc superconductors, show spin and charge density wave. The formation of an sdw with a corresponding spatial frequency causes the opening of an energy gap that lowers the systems energy. Superconductivity and spin density wave sdw in nafe1xco as.
The theoretical results are then applied to show the coexistence of superconductivity and spin density wave sdw in nafe 1x co x as. Theory of the competition between spin density waves and dwave. Theory predicts that coexistence of an sdw and superconductivity is possible where phases of the superconducting wave functions on different portions of the fermi surface with s gap symmetry are different by a factor of. Pdf hosted at the radboud repository of the radboud. At this doping level, the system is known to exhibit weak. Interplay between spin density wave and superconductivity. Brydon,2 and carsten timm1, 1institute of theoretical physics, technische universit. What are the significances of chargedensity waves cdw and. Superconductivity and spin density wave in two dimensional. The wave vector is consistent with our theoretical calculation for the fermi surface nesting vector, indicating that the.
The latter component is responsible for superconductivit. The full curve represents the nbse 3 density of states along the a axis at 1. The polymorph 4hnbse 2 undergoes a cdw transition at cdwt. Evidence of spin density wave in lafeaso, the parent. We present a meanfield theory theoretical model study for the coexistence of the two strongly interacting charge density wave cdw and spin density wave sdw for hight c cuprates in the underdoped region before the onset of the superconductivity in the system. The theory assumes local sdw order, and associated electron and hole pocket fermi surfaces of charge carriers in the normal state. Superconductivity and charge density wave in zrte 3. Pdf effect of chemical pressure on spin density wave and. Competition between charge and spin density wave order and superconductivity in la1. Any material exhibiting these properties is a superconductor. Dynamic competition between spindensity wave order and.
Coexistence of superconductivity and spin density wave sdw in. Spin density wave pair density wave spin nematic charge4 superconductivity strength1 cdw dislocation bound to. A charge density wave cdw is an ordered quantum fluid of electrons in a linear chain compound or layered crystal. In this research work, the theoretical investigation of the coexistence of spin density wave and superconductivity in bafe 2x co x as 2 has been made. Chargeorbital density wave and superconductivity in the. Density functional theory dft has been used on a arivety of metals and compounds to successfully describe their ground state properties. Retarded double time greens function formalism, spin singlet and triplet state, superconductivity and spin density wave. Your story matters citation moon, eun, and subir sachdev. Coexistence of superconductivity and chargedensity wave in the.
Spin density waves sdws may be thought of as comprising charge density waves cdws in pairs, with one cdw composed of up spin electrons and the other composed of down spin electrons. Cr is the prime example of an itinerant antiferromagnet, its incommensurate spin density wave sdw is a truly manybody e ect. Dynamic competition between spin density wave order and. The spin density wave quantum phase transition in two. Charge dynamics of the spindensitywave state in bafe. Annett university of bristol, department of physics, h. This spin density wave in turn causes a nearby electron to fall into the spin depression created by the first electron waterbed effect again. Microscopic coexistence of a twocomponent incommensurate. Coexistence of superconductivity and spin density wave sdw.
Charge density waves and superconductivity for a long time, physicists have tried to understand the relationship between a periodic pattern of conduction electrons called a charge density wave cdw, and another quantum order, superconductivity, or zero electrical resistance, in the same material. Coexistence of the spindensity wave and superconductivity. Chen et al 2009 epl 85 17006 view the article online for updates and enhancements. A theory for the coexistence problem of the spin density wave sdw and superconductivity sc in highly anisotropic materials is presented. This study focuses on the theoretical investigation of the coexistence of superconductivity and spin density wave sdw in a twoband model for the ironbased superconductor bafe2as1. Coherent charge and spin density waves in underdoped hgba cuo. The theoretical results are then applied to show the coexistence of spin density wave and superconductivity in iron pnictide compound ba 1x k x fe 2 as 2 0.
Find materials for this course in the pages linked along the left. Unconventional electronic reconstruction in undoped ba,sr. In the itinerant picture, the static af order arises from the nesting of the hole and electron fermi surfaces 7,8, much like the spindensitywave state of chromium 14. A spin density wave sdw within the iron atoms occupying regular tetrahedral sites was observed, with the square root of the mean square amplitude at 4. The results show that hfte3 is a promising new material to help study the relationship between sc and cdw. Coexistence of spin density wave and superconductivity in. By developing a model hamiltonian for the system and by using quantum field theory greens function formalism, we have obtained mathematical expressions for superconducting transition temperature t c, spin density wave transition. Other lowtemperature ground states that occur in such materials are superconductivity, ferromagnetism and antiferromagnetism.
Electron spectral function and optical conductivity at quantum critical point scattering off composite operators sunday, april 24, 2011. Charge and spindensitywave superconductors article pdf available in superconductor science and technology 144 april 2001 with 1,919 reads how we measure reads. The existence of the sdw in cr was first posited in 1960 by albert overhauser of purdue. Superconducting pairing in the spindensitywave phase of iron pnictides jacob schmiedt, 1, p. The theoretical results are then applied to show the coexistence of spin density wave and superconductivity in iron pnictide compound ba1xkxfe2as2 0. Pdf the coexistence of super conductivity and spin. Pdf superconductors with charge and spindensity waves. Superconducting pairing in the spindensitywave phase of. Superconductivity and spin density wave sdw in nafe1xco. Competition between spin density wave order and superconductivity. The relation between the spin density wave sdw and superconducting order is a central topic in the current research on the feasbased hight c superconductors. Impuritycontrolled superconductivityspin density wave. Aubansenzier et althis content was downloaded from ip address 207.
Pdf anomalous spin density wave superconductivity in. We also discovered that both pd intercalation and substitution induce bulk superconductivity with t c up to. A second problem for achieving hightemperature super conductivity is that strong effective attractions, which might be expected to produce a high pairing scale, typically lead to lattice instabilities, charge or spin density wave order, or twophase gasliquid or phaseseparated. We study the interplay between superconductivity and spin density wave order in graphene doped to 38 or 58 filling a van hove doping. An interplay between the superconductivity and spin density wave sdw is studied from the perturbative point of view based on the two dimensional hubbard model. However, distinct from the work in y123 this order has a rather di erent character. The calculations show that those fluctuations are the cause of superconductivity 3. This phenomenon is caused by the slight ariationv of.
Evolution of the spindensity wavesuperconductivity. With reference to the recent angleresolved photoemission experimental data in hight c cuprates, presence of the nested pieces of bands is assumed. Conflicting results exist in the lafeaso, fclass of materials, for which whether the sdw and superconductivity are mutually exclusive or they can coexist has not been settled. Division of physics, national research council of canada, ottawa, ontario kia or6 canada received 6 june 1983 by r. Pdf nodeless superconductivity in the presence of spin. The superconducting transition temperature of 2hnbse 2 is remarkably high in comparison with other tmds. Voitenko institute of physics, prospekt nauki 46, 03028 kiev28, ukraine j. Coexistence of spin density wave sdw and superconductivity. Both these states occur at low temperature in anisotropic, lowdimensional materials or in metals that have high densities of states at the fermi level.
Competition between spin density wave order and superconductivity in the underdoped cuprates, eun gook moon and s. Competition between spin density wave order and superconductivity in the underdoped. The microwave penetration depth is determined by the superfluid density responsible for screening the external field. Renormalisation group calculations reproduce this phase diagram, as well as the detailed evolution of the antiferromagnetic spin fluctuations with pressure and temperature. We predict that this itinerant nesting driven magnetic state is strongest in fete and in addition that fete has the largest fermi surface of the three compounds. The singleband hubbard model, therefore, when treated within the hatreefock mean field theory leads to a spin density wave sdw ground state. By tuning the coupling between magnetic and superconducting order, a phase with inhomogeneous p wave superconductivity can be detected, which coexists with d wave superconductivity and spin. Using the renormalization group method, we find that d or p wave superconductivity and charge or spin density wave emerge as the two types of leading instabilities driven by coulomb repulsion. Spindensity wave sdw and charge density wave cdw are names for two similar lowenergy ordered states of solids. Barrie infrared conductivity from an incommensurate spin density wave occurs due to.
A spin density wave in the topological insulator bi 2te 3 anjan soumyanarayanan massachusetts institute of technology may 11, 2010 abstract topological insulators are materials with a bulk band gap, but with topologically protected, spin polarized surface. Initial studies have hinted towards the possibility of a spin density wave sdw in these compounds and how they could play an important role in the superconductivity. A number of materials in the cuprate family, which includes the high. Hall conductivity of a moving magneticfieldinduced spin. Theory of the competition between spin density waves and d. Here, superconductivity occurs due to the signreversed superconducting order parameter. The density wave state has a gapped energy spectrum around n2 and. Superconductivity by joe khachan and stephen bosi the discovery of superconductors the phenomenon of superconductivity, in which the electrical resistance of certain materials completely vanishes at low temperatures, is one of the most interesting and sophisticated in condensed matter physics. A number of materials in the cuprate family, which includes the high transitiontemperature hight c superconductors, show spin and charge density wave order 5,6,7. Pdf the properties of existing superconductors with ejectron spectrum instabilities, namely chargedensity waves cdws and spindensity waves sdws, are. Charge density wave cdw, the periodic modulation of the electronic charge density, will open a gap on the fermi surface that commonly leads to decreased or vanishing conductivity. Direct observation of competition between superconductivity. It is temperature and magnetic eld independent and it is not induced by either.
The problem of the bcstobec crossover rst arose in an attempt to understand super conductivity and super uidity going beyond the standard paradigms. The spin density wave sdw and charge density wave cdw order in superconducting la1. This work focuses on the theoretical investigation of the coexistence of superconductivity and spin density wave sdw in ferropnictide ba 1. Pdf the coexistence of super conductivity and spin density.
Nodeless superconductivity in the presence of spin density wave in pnictide superconductors. Evolution from unconventional spin density wave to. Low energy theory of spin density wave quantum critical point 2. In the last decade a number of theories have been proposed to explain the anomalous behavior of this special class of chargetransfer salts. Superconductivity of electron and hole pockets in a background of.
It is shown that the dpairing superconductivity is induced by spin fluctuations near the sdw boundary. It is concluded that the sdw state is precluded when the sc state developes at a higher temperature. The underlying reasons of the electron spectrum instability may be. Pdf interplay of superconductivity and spin density wave. Competition between spin density wave order and superconductivity in the underdoped cuprates the harvard community has made this article openly available. The coexistence of super conductivity and spin density wave. Pdf on jan 1, 2014, dagne atnafu and others published the coexistence of super conductivity and spin density wave sdw in smo 1x f x feas find, read and cite all the research you need on. Effect of pnictogen height on spin waves in iron pnictides. The influence of the motion of a magneticfieldinduced spin density wave fisdw on the quantum hall effect in a quasionedimensional conductor is studied theoretically. The coexistence of super conductivity and spin density. The realspace periodicity of the resulting spin density wave is given by. Symmetrybreaking orbital anisotropy observed for detwinned ba. Unconventional superconductivity and density waves in.
The superconductivity in cuprates may then be said to be caused by the bcstype pairing of these sdws. Dynamic competition between spin density wave order and superconductivity in underdoped ba 1. When the system temperature is lowered, more spin density waves and cooper pairs are. The electrons in such a cdw, like those in a superconductor, can flow through a linear chain compound en masse, in a highly correlated fashion. Pdf competition between charge and spindensitywave. Fs nesting are found in the doping levels relevant to the correlated insulator and unconventional superconductivity revealed experimentally, base on which we identify the two phases as weakcoupling fs instabilities. Thus for 16 k spin density wave and superconductivity in underdoped nafe. Condensed matter physics copyright 2019 unconventional. This wide range of behaviors suggests that electronic ordering and super conductivity may not be intimately connected. Wills physics laboratory, royal fort, tyndall avenue, bristol bs8 ttl, united kingdom. Spingap proximity effect mechanism of hightemperature. One of the most surprising results in condensed matter physics is that a fermi liquid i. The coexistence of superconductivity and spin density wave in smo1.
Besides, other experimental and theoretical findings, especially the antiferromagnetic ground state and the sdw anomaly of lafeaso strongly suggest that the pairing mechanism of the electrons is likely to be connected. Interplay between spin density wave and superconductivity in arxiv. However, the discovery of superconductivity in socalled iron based pnictides 25 revealed a novel class of hight c superconductors with a multiple band structure where super conductivity may coexist with spin density wave, thus con. Interplay of charge density wave and spin density wave in. When superconductivity coexists with a spin density wave sdw for the same. We study the interplay between superconductivity and spindensitywave order in graphene doped to 38 or 58 filling a van hove doping.
The work is motivated by the recent experimental evidences of coexistence of spin density wave and superconductivity in a number of feasbased superconductors. Infrared conductivity from spin and charge density waves. The analytic expressions for the temperature dependence of the cdw and sdw order parameters are derived and solved selfconsistently. This work is focused on the transition metal chromium. In the s wave bcs theory, because pairs can be thermally excited across the gap. Interplay of spin density wave and superconductivity with. In the ironpnictides, these competing phases are marked by a tetragonaltoorthorhombic structural transition and a collinear spin density wave sdw transition. A model study for the coexistence of the spin density wave and superconductivity is presented. The superconducting state can be reached by substituting with elements that add holes or electrons hole or electron doping, by applying pressure, or even by replacing. On the basis of a simplified electronic band model a hartreefock approximation is applied. Superconductivity is the set of physical properties observed in certain materials, wherein electrical resistance vanishes and from which magnetic flux fields are expelled. Interplay between spin density wave and superconductivity in.
Spindensity wave sdw and chargedensity wave cdw are names for two similar. Effect of chemical pressure on spin density wave and superconductivity in undoped and 15% fdoped la1yyyfeaso compounds. Interplay of superconductivity and spindensitywave order. Employing green function formalism, the expression for the spin density wave order. There has been macroscopic evidence for competition between these phases and superconductivity as the magnitude of both the orthorhombicity and magnetic moment are. Coexistence of the spindensity wave and superconductivity in ba 1x k x fe 2 as 2 to cite this article. Model hamiltonian of the system the purpose of this work is to study theoretically the coexistence of spin density wave and superconductivity properties in the compound ba 1. Visualizing the microscopic coexistence of spin density wave and superconductivity in underdoped nafe 1.
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