Pub Date : 1985-09-01DOI: 10.1051/JPHYSLET:019850046017084500
U. Krey
The density of states of magnon-like excitations of Eu x Sr 1−x S spin glasses with x=0.25, 0.44 and 0.54 is calculated for very strong magnetic fields B, i.e. B>3 T. It is found that for these high fields the magnon-like excitations can be treated as non-interacting bosons up to temperatures far beyond the spin glass freezing temperature at B=0. From the density of states the magnetic part C H of the specific heat is calculated, without any fit-parameter. The results agree quantitatively with recent experiments, for T between 0.3 K and 5 K (10 K) in magnetic fields of 3.6 T (6.6 T) Etude des excitations de quasi-magnons dans ces composes pour x=0,25, 0,44 et 0,54 en champ magnetique intense (B>3 T). Traitement de ces quasi-magnons comme des bosons non interagissants bien au-dessous de la temperature de transition de verre de spin a B=0. Calcul, sans parametre ajustable, de la densite d'etats des magnons et de la chaleur massique magnetique
在强磁场B(即B>3 t)条件下，计算了x=0.25、0.44和0.54的Eu x Sr 1−x S自旋玻璃的类磁振子激发态密度，发现在这些强磁场下，类磁振子激发态可以被视为非相互作用玻色子，直至远超过自旋玻璃冻结温度B=0的温度。由态密度计算出比热的磁性部分hc，不需要任何拟合参数。在3.6 T (6.6 T)的磁场中，当T在0.3 K到5 K (10 K)之间时，研究了准磁振子的激发，结果与最近的实验结果一致，当x= 0,25,0,44和0,54时，磁性强(B>3 T)，准磁振子的性质与非相互作用的玻色子的性质一致，温度，转变，自旋，B=0。计算，无参数可调，关于磁振子和磁振子的密度
{"title":"Magnon excitations and the specific heat of EuxSr1- xS spin glasses in strong magnetic fields","authors":"U. Krey","doi":"10.1051/JPHYSLET:019850046017084500","DOIUrl":"https://doi.org/10.1051/JPHYSLET:019850046017084500","url":null,"abstract":"The density of states of magnon-like excitations of Eu x Sr 1−x S spin glasses with x=0.25, 0.44 and 0.54 is calculated for very strong magnetic fields B, i.e. B>3 T. It is found that for these high fields the magnon-like excitations can be treated as non-interacting bosons up to temperatures far beyond the spin glass freezing temperature at B=0. From the density of states the magnetic part C H of the specific heat is calculated, without any fit-parameter. The results agree quantitatively with recent experiments, for T between 0.3 K and 5 K (10 K) in magnetic fields of 3.6 T (6.6 T) Etude des excitations de quasi-magnons dans ces composes pour x=0,25, 0,44 et 0,54 en champ magnetique intense (B>3 T). Traitement de ces quasi-magnons comme des bosons non interagissants bien au-dessous de la temperature de transition de verre de spin a B=0. Calcul, sans parametre ajustable, de la densite d'etats des magnons et de la chaleur massique magnetique","PeriodicalId":14822,"journal":{"name":"Journal De Physique Lettres","volume":"102 1","pages":"845-850"},"PeriodicalIF":0.0,"publicationDate":"1985-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85835668","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1985-08-01DOI: 10.1051/JPHYSLET:019850046016071900
S. Hikami
The problem of Anderson localization in a strong spin-orbit coupling case is studied by using a gauge invariant matrix model in e=4-d expansion. An infrared stable fixed point is present and this model belongs to the same universal class as a nonlinear σ model. An expression for the critical exponent of conductivity is obtained in the first order of the e-expansion Etude de cette localisation a l'aide d'un modele matriciel a invariance de jauge: presence d'un point fixe stable dans l'IR et appartenance du modele a la meme classe d'universalite que le modele σ non lineaire. Expression pour l'exposant de la conductivite au 1er ordre en e
{"title":"4 — d expansion for Anderson localization in a strong spin-orbit coupling case","authors":"S. Hikami","doi":"10.1051/JPHYSLET:019850046016071900","DOIUrl":"https://doi.org/10.1051/JPHYSLET:019850046016071900","url":null,"abstract":"The problem of Anderson localization in a strong spin-orbit coupling case is studied by using a gauge invariant matrix model in e=4-d expansion. An infrared stable fixed point is present and this model belongs to the same universal class as a nonlinear σ model. An expression for the critical exponent of conductivity is obtained in the first order of the e-expansion Etude de cette localisation a l'aide d'un modele matriciel a invariance de jauge: presence d'un point fixe stable dans l'IR et appartenance du modele a la meme classe d'universalite que le modele σ non lineaire. Expression pour l'exposant de la conductivite au 1er ordre en e","PeriodicalId":14822,"journal":{"name":"Journal De Physique Lettres","volume":"56 1","pages":"719-722"},"PeriodicalIF":0.0,"publicationDate":"1985-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91063391","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1985-08-01DOI: 10.1051/JPHYSLET:019850046016075100
B. Duplantier
We consider an isolated polymer chain in a good solvent and calculate the swelling of an arbitrary part of it. We show that this swelling is much more important in the central part of the chain, and decreases abruptly when one reaches one of its extremities. We give the expressions of the averages of all the powers of the distance between two arbitrary points of the chain, at first order in e = 4 - d, d being the space dimension. Critical indices are deduced from it.
{"title":"Swelling of the various parts of a polymer chain in a good solvent","authors":"B. Duplantier","doi":"10.1051/JPHYSLET:019850046016075100","DOIUrl":"https://doi.org/10.1051/JPHYSLET:019850046016075100","url":null,"abstract":"We consider an isolated polymer chain in a good solvent and calculate the swelling of an arbitrary part of it. We show that this swelling is much more important in the central part of the chain, and decreases abruptly when one reaches one of its extremities. We give the expressions of the averages of all the powers of the distance between two arbitrary points of the chain, at first order in e = 4 - d, d being the space dimension. Critical indices are deduced from it.","PeriodicalId":14822,"journal":{"name":"Journal De Physique Lettres","volume":"9 1","pages":"751-758"},"PeriodicalIF":0.0,"publicationDate":"1985-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75438787","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1985-08-01DOI: 10.1051/JPHYSLET:019850046016075900
A. Jákli, L. Bata, A. Buka, N. Éber, I. Jánossy
A new electromechanical effect has been found in planar oriented S c liquid crystals under the influence of an applied alternating electric field. A part from the well-known electrooptical effects a mechanical vibration has been observed in a direction parallel to the smectic layers and perpendicular to the electric field Observation de vibrations mecaniques induites par un champ electrique alternatif, dans la direction parallele aux couches smectiques et perpendiculairement au champ electrique
{"title":"New electromechanical effect in chiral smectic C* liquid crystals","authors":"A. Jákli, L. Bata, A. Buka, N. Éber, I. Jánossy","doi":"10.1051/JPHYSLET:019850046016075900","DOIUrl":"https://doi.org/10.1051/JPHYSLET:019850046016075900","url":null,"abstract":"A new electromechanical effect has been found in planar oriented S c liquid crystals under the influence of an applied alternating electric field. A part from the well-known electrooptical effects a mechanical vibration has been observed in a direction parallel to the smectic layers and perpendicular to the electric field Observation de vibrations mecaniques induites par un champ electrique alternatif, dans la direction parallele aux couches smectiques et perpendiculairement au champ electrique","PeriodicalId":14822,"journal":{"name":"Journal De Physique Lettres","volume":"3 4","pages":"759-761"},"PeriodicalIF":0.0,"publicationDate":"1985-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72593447","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1985-08-01DOI: 10.1051/JPHYSLET:019850046016072300
M. Kleman
Etude theorique des ordres nematiques et cholesteriques des cristaux liquides polymeriques; suggestion des developpements relatifs a l'ordre local des polymeres fondus
聚合物液晶向列有序和胆固醇有序的理论研究;关于熔融聚合物局部顺序的发展建议
{"title":"Frustration in polymers","authors":"M. Kleman","doi":"10.1051/JPHYSLET:019850046016072300","DOIUrl":"https://doi.org/10.1051/JPHYSLET:019850046016072300","url":null,"abstract":"Etude theorique des ordres nematiques et cholesteriques des cristaux liquides polymeriques; suggestion des developpements relatifs a l'ordre local des polymeres fondus","PeriodicalId":14822,"journal":{"name":"Journal De Physique Lettres","volume":"51 1","pages":"723-732"},"PeriodicalIF":0.0,"publicationDate":"1985-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89441860","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1985-08-01DOI: 10.1051/JPHYSLET:019850046016074500
C. Gonella, C. Gil, P. Louvet
When a particle beam is injected through a spatially periodic modulated mirror, under special initial conditions, one obtains a resonant exchange of energy from the longitudinal to the transverse component of the particle velocity. The equations of motion are solved and the growth of the Larmor radius is predicted Lorsque l'on injecte un faisceau de particules dans une structure periodique a miroirs faiblement modules, on obtient pour certaines conditions initiales un transfert d'energie resonnant entre energie longitudinale et transversale. La resolution des equations du mouvement permet de deduire la croissance du rayon de Larmor
{"title":"Chauffage de particules dans une structure magnétique périodique","authors":"C. Gonella, C. Gil, P. Louvet","doi":"10.1051/JPHYSLET:019850046016074500","DOIUrl":"https://doi.org/10.1051/JPHYSLET:019850046016074500","url":null,"abstract":"When a particle beam is injected through a spatially periodic modulated mirror, under special initial conditions, one obtains a resonant exchange of energy from the longitudinal to the transverse component of the particle velocity. The equations of motion are solved and the growth of the Larmor radius is predicted Lorsque l'on injecte un faisceau de particules dans une structure periodique a miroirs faiblement modules, on obtient pour certaines conditions initiales un transfert d'energie resonnant entre energie longitudinale et transversale. La resolution des equations du mouvement permet de deduire la croissance du rayon de Larmor","PeriodicalId":14822,"journal":{"name":"Journal De Physique Lettres","volume":"26 1","pages":"745-749"},"PeriodicalIF":0.0,"publicationDate":"1985-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87525832","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1985-08-01DOI: 10.1051/JPHYSLET:019850046015066700
R. Rammal, A. Benoît
A new efficient algorithm for determining the energy barrier to overturn a finite cluster of ferromagnetic Ising spin is described. Percolation clusters at threshold are used to illustrate our method. We show in particular that the energy barrier scales logarithmically with the cluster size in contrast with the known power law behaviour on Euclidean lattices. Some of the consequences of this result for the kinetic Ising model on diluted ferromagnets are briefly discussed On decrit un nouvel algorithme efficace pour determiner la barriere d'energie de retournement d'un amas fini de spins d'Ising ferromagnetiques. Cette methode est illustree dans le cas des amas de percolation au seuil. On montre que la barriere augmente comme le logarithme de la taille au lieu d'une loi de puissance bien connue dans les reseaux euclidiens. Certaines consequences de ces resultats pour le modele d'Ising cinetique sur les ferromagnetiques dilues sont brievement discutees
描述了一种新的有效算法来确定推翻有限铁磁伊辛自旋簇的能垒。阈值处的渗透聚类用来说明我们的方法。我们特别表明，与已知的欧几里得晶格上的幂律行为相反，能量势垒与簇大小成对数关系。本文简要讨论了这一结果对稀释铁磁体的动力学Ising模型的一些影响，并提出了一种新的算法，即效率决定因素、能量障碍、能量恢复、自旋和Ising铁磁体的自旋。本文介绍了该方法在渗滤过程中的应用。在montre que la barrier上，增加了la taille的对数，增加了la taille的对数，增加了la taille的对数，增加了la taille的对数。某些结果导致了对铁磁流体动力学模型的简化讨论
{"title":"Energy barriers of the Ising model on percolation clusters : a numerical study","authors":"R. Rammal, A. Benoît","doi":"10.1051/JPHYSLET:019850046015066700","DOIUrl":"https://doi.org/10.1051/JPHYSLET:019850046015066700","url":null,"abstract":"A new efficient algorithm for determining the energy barrier to overturn a finite cluster of ferromagnetic Ising spin is described. Percolation clusters at threshold are used to illustrate our method. We show in particular that the energy barrier scales logarithmically with the cluster size in contrast with the known power law behaviour on Euclidean lattices. Some of the consequences of this result for the kinetic Ising model on diluted ferromagnets are briefly discussed On decrit un nouvel algorithme efficace pour determiner la barriere d'energie de retournement d'un amas fini de spins d'Ising ferromagnetiques. Cette methode est illustree dans le cas des amas de percolation au seuil. On montre que la barriere augmente comme le logarithme de la taille au lieu d'une loi de puissance bien connue dans les reseaux euclidiens. Certaines consequences de ces resultats pour le modele d'Ising cinetique sur les ferromagnetiques dilues sont brievement discutees","PeriodicalId":14822,"journal":{"name":"Journal De Physique Lettres","volume":"43 1 1","pages":"667-673"},"PeriodicalIF":0.0,"publicationDate":"1985-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90032422","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1985-08-01DOI: 10.1051/JPHYSLET:019850046015068300
M. Gharbia, M. Cagnon, G. Durand
We present the first observation of an undulation instability of the columns in a tubular discotic liquid crystal when submitted to a dilation normal to the columns. This effect is very similar to the layer undulation in smectic materials. From the instability threshold and from the undulation wavelength, we derive a value, anomalously large, of the column curvature elastic constant, very close to the value obtained from observation of the column buckling under longitudinal compression. The static or dynamic origin of such a large curvature elastic constant is not understood Presentation de la premiere observation d'une instabilite d'ondulation des colonnes dans un cristal discotique tubulaire lorsqu'il est soumis a une dilatation normale aux colonnes. Deduction d'une valeur anormalement elevee de la constante elastique de courbure des colonnes a partir du seuil d'instabilite et de la longueur d'onde des ondulations
我们首次观察到管状盘状液晶中圆柱在正常膨胀时的波动不稳定性。这种效应与近晶材料中的层状波动非常相似。根据失稳阈值和波动波长，我们得到了一个异常大的柱曲率弹性常数值，与纵向压缩下柱屈曲的观测值非常接近。如此大的曲率弹性常数的静态或动态起源尚不清楚。首次观察d' unstabilite d'ondulation des colonens和uncrystal盘状管状lorsquil ' est soumis a one expansion normale aux colonens。推导出一种值的非规定值，即一种常数的弹性，一种非规定值的弹性，一种非规定值的弹性，一种非规定值的弹性，一种非规定值的弹性，一种非规定值的弹性，一种非规定值的弹性
{"title":"Column undulation instability in a discotic liquid crystal","authors":"M. Gharbia, M. Cagnon, G. Durand","doi":"10.1051/JPHYSLET:019850046015068300","DOIUrl":"https://doi.org/10.1051/JPHYSLET:019850046015068300","url":null,"abstract":"We present the first observation of an undulation instability of the columns in a tubular discotic liquid crystal when submitted to a dilation normal to the columns. This effect is very similar to the layer undulation in smectic materials. From the instability threshold and from the undulation wavelength, we derive a value, anomalously large, of the column curvature elastic constant, very close to the value obtained from observation of the column buckling under longitudinal compression. The static or dynamic origin of such a large curvature elastic constant is not understood Presentation de la premiere observation d'une instabilite d'ondulation des colonnes dans un cristal discotique tubulaire lorsqu'il est soumis a une dilatation normale aux colonnes. Deduction d'une valeur anormalement elevee de la constante elastique de courbure des colonnes a partir du seuil d'instabilite et de la longueur d'onde des ondulations","PeriodicalId":14822,"journal":{"name":"Journal De Physique Lettres","volume":"37 1","pages":"683-687"},"PeriodicalIF":0.0,"publicationDate":"1985-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90043926","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1985-08-01DOI: 10.1051/JPHYSLET:019850046016073300
V. Velasco, F. García-Moliner
The surface contributions to the total density of states, which determine the temperature dependence of the surface specific heat, are very simply obtained by a direct application of the surface Green function matching analysis to an inviscid liquid. A discrepancy on the low temperature behaviour is resolved while showing the connection with the theory of another surface spectral function of physical interest Calcul des contributions de surface a la densite d'etats totale qui determine la variation thermique de la chaleur massique de surface, par application directe de la methode d'adaptation des fonctions de Green de surface du liquide non visqueux. Interpretation du comportement a basse temperature
{"title":"Spectral functions for a semi-infinite liquid","authors":"V. Velasco, F. García-Moliner","doi":"10.1051/JPHYSLET:019850046016073300","DOIUrl":"https://doi.org/10.1051/JPHYSLET:019850046016073300","url":null,"abstract":"The surface contributions to the total density of states, which determine the temperature dependence of the surface specific heat, are very simply obtained by a direct application of the surface Green function matching analysis to an inviscid liquid. A discrepancy on the low temperature behaviour is resolved while showing the connection with the theory of another surface spectral function of physical interest Calcul des contributions de surface a la densite d'etats totale qui determine la variation thermique de la chaleur massique de surface, par application directe de la methode d'adaptation des fonctions de Green de surface du liquide non visqueux. Interpretation du comportement a basse temperature","PeriodicalId":14822,"journal":{"name":"Journal De Physique Lettres","volume":"R-32 1","pages":"733-735"},"PeriodicalIF":0.0,"publicationDate":"1985-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84758142","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1985-08-01DOI: 10.1007/978-94-009-3783-3_3
J. Gambaudo, P. Glendinning, C. Tresser
{"title":"Stable Cycles with Complicated Structure","authors":"J. Gambaudo, P. Glendinning, C. Tresser","doi":"10.1007/978-94-009-3783-3_3","DOIUrl":"https://doi.org/10.1007/978-94-009-3783-3_3","url":null,"abstract":"","PeriodicalId":14822,"journal":{"name":"Journal De Physique Lettres","volume":"11 1","pages":"41-62"},"PeriodicalIF":0.0,"publicationDate":"1985-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75194881","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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