Pub Date : 1985-07-01DOI: 10.1051/JPHYSLET:019850046014063100
M. Kolb
Angular correlations are calculated inside aggregation clusters of diffusion limited particle (PA) and cluster (CA) aggregation. The aggregates are isotropic for CA but anisotropic for PA, scaling differently parallel and perpendicular to the direction of growth. The correlation function exponents in two dimensions differ by ΔA=0,16±0,05 in the two directions. This leads to correction to scaling effects, especially for growth on a lattice Les correlations angulaires sont calculees a l'interieur des amas obtenus par collage de particules (PA) et par collage d'amas (CA). Alors que les amas sont isotropes pour CA, ils sont anisotropes pour PA. Les exposants de la fonction de correlation en deux dimensions, parallele et perpendiculaire a la direction de croissance, different de ΔA=0,16±0,05 pour Pa. Ceci introduit des corrections aux lois d'echelle.
计算了扩散受限粒子(PA)和聚类(CA)聚集簇内的角相关性。CA的聚集体是各向同性的，而PA的聚集体是各向异性的，在生长方向上平行和垂直的尺度不同。两个维度上的相关函数指数在两个方向上相差ΔA=0,16±0,05。这导致了尺度效应的修正，特别是对于晶格上的生长，Les correlation angulaires soncullees a 'interieur des amas obtenus par collage de particles (PA)和par collage d'amas (CA)。CA的各向同性和PA的各向异性是不同的。两个维度上的关联度，平行垂直方向上的关联度，不同的关联度ΔA=0,16±0,05 pour Pa。塞西介绍了“梯队法”的修正。
{"title":"Effects of the growth mechanism on the structure of aggregation clusters","authors":"M. Kolb","doi":"10.1051/JPHYSLET:019850046014063100","DOIUrl":"https://doi.org/10.1051/JPHYSLET:019850046014063100","url":null,"abstract":"Angular correlations are calculated inside aggregation clusters of diffusion limited particle (PA) and cluster (CA) aggregation. The aggregates are isotropic for CA but anisotropic for PA, scaling differently parallel and perpendicular to the direction of growth. The correlation function exponents in two dimensions differ by ΔA=0,16±0,05 in the two directions. This leads to correction to scaling effects, especially for growth on a lattice Les correlations angulaires sont calculees a l'interieur des amas obtenus par collage de particules (PA) et par collage d'amas (CA). Alors que les amas sont isotropes pour CA, ils sont anisotropes pour PA. Les exposants de la fonction de correlation en deux dimensions, parallele et perpendiculaire a la direction de croissance, different de ΔA=0,16±0,05 pour Pa. Ceci introduit des corrections aux lois d'echelle.","PeriodicalId":14822,"journal":{"name":"Journal De Physique Lettres","volume":"27 1","pages":"631-637"},"PeriodicalIF":0.0,"publicationDate":"1985-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88626096","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 : 1985-07-01DOI: 10.1051/JPHYSLET:019850046013059500
J. D. Cloizeaux, R. Conte, G. Jannink
In the framework of the continuous model, a precise expression of the swelling of an isolated polymer in solution is given for all values of the interaction. The perturbation series obtained by Muthukumar and Nickel (1984) constitutes the initial data and a « direct renormalization method » is used to get the final result (in three dimensions).
{"title":"Swelling of an isolated polymer chain in a solvent","authors":"J. D. Cloizeaux, R. Conte, G. Jannink","doi":"10.1051/JPHYSLET:019850046013059500","DOIUrl":"https://doi.org/10.1051/JPHYSLET:019850046013059500","url":null,"abstract":"In the framework of the continuous model, a precise expression of the swelling of an isolated polymer in solution is given for all values of the interaction. The perturbation series obtained by Muthukumar and Nickel (1984) constitutes the initial data and a « direct renormalization method » is used to get the final result (in three dimensions).","PeriodicalId":14822,"journal":{"name":"Journal De Physique Lettres","volume":"48 1","pages":"595-600"},"PeriodicalIF":0.0,"publicationDate":"1985-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76267410","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 : 1985-07-01DOI: 10.1051/JPHYSLET:019850046013057500
S. Grossmann, F. Wegner, K. Hoffmann
The temporal increase of the moments in diffusion on a fractal with variable hopping range and lower cut-off is given. The essential parameters are the growth ratio, the length scaling and, as a new feature, the time scaling along the hierarchy. We find algebraical or exponential increase, logarithmic corrections, or trapping if the cut-off is removed. For the first time anomalous enhancement of the variance increase σ'0 tθ, θ larger than 2, is obtained as observed in turbulence On etudie la croissance temporelle des moments de la distribution de particules diffusant sur un fractal a portee de saut variable avec une coupure inferieure. Les parametres essentiels sont: le taux de croissance, le facteur d'echelle de la longueur et celui du temps le long de la hierarchie, ce dernier critere est nouveau. On trouve des lois de croissance algebriques et exponentielles et des corrections logarithmiques, ou un piegeage si la coupure est eliminee. Une augmentation anormale du taux de croissance de la variance σαtθ, θ>2, comme cela a deja ete observe pour la turbulence, est obtenue pour la 1ere fois
{"title":"Anomalous diffusion on a selfsimilar hierarchical structure","authors":"S. Grossmann, F. Wegner, K. Hoffmann","doi":"10.1051/JPHYSLET:019850046013057500","DOIUrl":"https://doi.org/10.1051/JPHYSLET:019850046013057500","url":null,"abstract":"The temporal increase of the moments in diffusion on a fractal with variable hopping range and lower cut-off is given. The essential parameters are the growth ratio, the length scaling and, as a new feature, the time scaling along the hierarchy. We find algebraical or exponential increase, logarithmic corrections, or trapping if the cut-off is removed. For the first time anomalous enhancement of the variance increase σ'0 tθ, θ larger than 2, is obtained as observed in turbulence On etudie la croissance temporelle des moments de la distribution de particules diffusant sur un fractal a portee de saut variable avec une coupure inferieure. Les parametres essentiels sont: le taux de croissance, le facteur d'echelle de la longueur et celui du temps le long de la hierarchie, ce dernier critere est nouveau. On trouve des lois de croissance algebriques et exponentielles et des corrections logarithmiques, ou un piegeage si la coupure est eliminee. Une augmentation anormale du taux de croissance de la variance σαtθ, θ>2, comme cela a deja ete observe pour la turbulence, est obtenue pour la 1ere fois","PeriodicalId":14822,"journal":{"name":"Journal De Physique Lettres","volume":"193 1","pages":"575-583"},"PeriodicalIF":0.0,"publicationDate":"1985-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75698307","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 : 1985-07-01DOI: 10.1051/JPHYSLET:019850046013059100
D. Poenaru, M. Ivaşcu
Résumé. 2014 La possibilité de nouveaux modes de radioactivité par émission spontanée de deux ou trois particules 03B1 ou de deux ions lourds identiques ou différents est envisagée. La variante analytique du modèle de la fission super-asymétrique est utilisée pour estimer les durées de vie. Abstract. 2014 New decay modes by spontaneous emission of two and three 03B1 particles and two iden-tical or different heavy ions, are predicted. The analytical variant of the superasymmetric fission model is used to estimate the half lives.
通过自发发射两个或三个03B1粒子或两个相同或不同的重离子，提出了新的放射性模式的可能性。超不对称裂变模型的解析变体被用来估计寿命。预测了两个和三个03B1粒子和两个相同或不同的重离子自发发射的新衰变模态。时变分析of The superasymmetric model is used to estimate The lives长大的裂变。
{"title":"Two alpha, three alpha and multiple heavy-ion radioactivities","authors":"D. Poenaru, M. Ivaşcu","doi":"10.1051/JPHYSLET:019850046013059100","DOIUrl":"https://doi.org/10.1051/JPHYSLET:019850046013059100","url":null,"abstract":"Résumé. 2014 La possibilité de nouveaux modes de radioactivité par émission spontanée de deux ou trois particules 03B1 ou de deux ions lourds identiques ou différents est envisagée. La variante analytique du modèle de la fission super-asymétrique est utilisée pour estimer les durées de vie. Abstract. 2014 New decay modes by spontaneous emission of two and three 03B1 particles and two iden-tical or different heavy ions, are predicted. The analytical variant of the superasymmetric fission model is used to estimate the half lives.","PeriodicalId":14822,"journal":{"name":"Journal De Physique Lettres","volume":"54 1","pages":"591-594"},"PeriodicalIF":0.0,"publicationDate":"1985-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74630767","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 : 1985-07-01DOI: 10.1051/JPHYSLET:019850046013058500
L. Arcangelis, S. Redner, H. Herrmann
We introduce and study a simple idealized model to describe breaking processes by analysing the current-carrying properties of a random network consisting of insulators and fuses. By increasing the value of the external voltage applied across the network, a sequence of fuses will « burn out » and change irreversible into insultating bonds. This process terminates when a conducting path no longer exists in the network. We monitor several basic quantities during this breaking process, such as the conductivity of the network and the value of the voltage needed to break the hottest fuse. Two new exponents describing the behaviour of these quantities near the percolation threshold are reported.
{"title":"A random fuse model for breaking processes","authors":"L. Arcangelis, S. Redner, H. Herrmann","doi":"10.1051/JPHYSLET:019850046013058500","DOIUrl":"https://doi.org/10.1051/JPHYSLET:019850046013058500","url":null,"abstract":"We introduce and study a simple idealized model to describe breaking processes by analysing the current-carrying properties of a random network consisting of insulators and fuses. By increasing the value of the external voltage applied across the network, a sequence of fuses will « burn out » and change irreversible into insultating bonds. This process terminates when a conducting path no longer exists in the network. We monitor several basic quantities during this breaking process, such as the conductivity of the network and the value of the voltage needed to break the hottest fuse. Two new exponents describing the behaviour of these quantities near the percolation threshold are reported.","PeriodicalId":14822,"journal":{"name":"Journal De Physique Lettres","volume":"14 1","pages":"585-590"},"PeriodicalIF":0.0,"publicationDate":"1985-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82501386","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 : 1985-07-01DOI: 10.1051/JPHYSLET:019850046014063900
P. Gennes
If a polymer chain is transferred abruptly from θ conditions to bad solvent conditions (e.g. by a shift of temperature ΔT) it collapses with a certain characteristic time τc. We propose a scaling structure for τc, based on an « expanding sausage model », and taking into account the hydrodynamic interactions. We find that τ c ≅ τR ΔT/θ where τR is the Rouse time of the θ chain : the time τc increases with the depth of quench.
如果聚合物链突然从θ条件转移到不良溶剂条件(例如，通过温度的变化ΔT)，它会以一定的特征时间τc崩溃。我们提出了一个尺度结构的τc，基于«膨胀香肠模型»，并考虑到水动力的相互作用。我们发现τc = τ r ΔT/θ，其中τ r为θ链的劳斯时间:时间τc随淬火深度的增加而增加。
{"title":"Kinetics of collapse for a flexible coil","authors":"P. Gennes","doi":"10.1051/JPHYSLET:019850046014063900","DOIUrl":"https://doi.org/10.1051/JPHYSLET:019850046014063900","url":null,"abstract":"If a polymer chain is transferred abruptly from θ conditions to bad solvent conditions (e.g. by a shift of temperature ΔT) it collapses with a certain characteristic time τc. We propose a scaling structure for τc, based on an « expanding sausage model », and taking into account the hydrodynamic interactions. We find that τ c ≅ τR ΔT/θ where τR is the Rouse time of the θ chain : the time τc increases with the depth of quench.","PeriodicalId":14822,"journal":{"name":"Journal De Physique Lettres","volume":"57 1","pages":"639-642"},"PeriodicalIF":0.0,"publicationDate":"1985-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79804839","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 : 1985-07-01DOI: 10.1051/JPHYSLET:019850046014064700
M. Ocio, H. Bouchiat, P. Monod
We observe spontaneous magnetic fluctuations at 4,2 K in zero field for the amorphous spin glass (Al 2 O 3 ) 0,1 (MNO) 0,5 (SiO 2 ) 0,4 and for the crystalline spin glass compound CsNiFeF 6 . In both cases the noise power spectrum exhibits an 1/f dependence in the range 10 −2 Hz to 10 2 Hz. The 1/f noise amplitude is in good agreement with the measured value of the out of phase susceptibility. This observation supports the applicability of the fluctuation dissipation theorem to spin glasses and suggests the magnetic noise as a new area of investigation Observation de fluctuations spontanees de l'aimantation a 4,2 K, en champ nul, dans le verre de spin amorphe (Al 2 O 3 ) 0,1 (MnO) 0,5 (SiO 2 ) 0,4 et dans le verre de spin cristallin CsNiFeF 6 : variation en 1/F de la densite spectrale pour des frequences de 10 −2 −10 2 Hz
我们观察了非晶自旋玻璃(Al 2o3) 0,1 (MNO) 0,5 (sio2) 0,4和晶体自旋玻璃化合物csnifef6在4,2 K零场下的自发磁波动。在这两种情况下，噪声功率谱在10−2 Hz至10.2 Hz范围内呈1/f依赖性。1/f噪声幅值与失相磁化率的测量值吻合较好。这一观测结果支持了涨落耗散定理在自旋玻璃上的适用，并提出了磁噪声作为一个新的研究领域。观测了自旋玻璃的自发涨落(4,2 K, en champ nul, dans le verre de自旋变形(Al 2o3) 0,1 (MnO) 0,5 (sio2) 0,4, dans le verre de自旋结晶(csnifef6):在频率为10−2−10 2hz时，密度谱的变化(en 1/F)
{"title":"Observation of 1/f magnetic fluctuations in a spin glass","authors":"M. Ocio, H. Bouchiat, P. Monod","doi":"10.1051/JPHYSLET:019850046014064700","DOIUrl":"https://doi.org/10.1051/JPHYSLET:019850046014064700","url":null,"abstract":"We observe spontaneous magnetic fluctuations at 4,2 K in zero field for the amorphous spin glass (Al 2 O 3 ) 0,1 (MNO) 0,5 (SiO 2 ) 0,4 and for the crystalline spin glass compound CsNiFeF 6 . In both cases the noise power spectrum exhibits an 1/f dependence in the range 10 −2 Hz to 10 2 Hz. The 1/f noise amplitude is in good agreement with the measured value of the out of phase susceptibility. This observation supports the applicability of the fluctuation dissipation theorem to spin glasses and suggests the magnetic noise as a new area of investigation Observation de fluctuations spontanees de l'aimantation a 4,2 K, en champ nul, dans le verre de spin amorphe (Al 2 O 3 ) 0,1 (MnO) 0,5 (SiO 2 ) 0,4 et dans le verre de spin cristallin CsNiFeF 6 : variation en 1/F de la densite spectrale pour des frequences de 10 −2 −10 2 Hz","PeriodicalId":14822,"journal":{"name":"Journal De Physique Lettres","volume":"39 1","pages":"647-652"},"PeriodicalIF":0.0,"publicationDate":"1985-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78213734","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 : 1985-07-01DOI: 10.1051/JPHYSLET:019850046014064300
L. Gor’kov, D. Jérome
It is shown that the properties of the upper critical fields in organic superconductors can be understood in terms of pure TYPE II superconductivity. The experimental observation of high critical fields violating Clogston's criterion could give support in favour of triplet-paired superconductivity Etude theorique montrant que les valeurs des champs critiques superieurs peuvent s'interpreter dans le cadre de la theorie des supraconducteurs propres de type II. Possibilite d'existence du supraconduction avec couplage triplet si l'on observe des valeurs depassant la limite de Clogston
结果表明，有机超导体上临界场的性质可以用纯II型超导性来理解。对违反Clogston准则的高临界场的实验观察，可以支持三重对超导性的理论(Etude theory montrant que les valeurers des champs)和解释(lecadre de la theories des superconducting pres type II)。超导现象存在的可能性，偶联三重态存在的可能性，在此基础上观察了超导现象在克罗格斯顿极限下的应用
{"title":"Back to the problem of the upper critical fields in organic superconductors","authors":"L. Gor’kov, D. Jérome","doi":"10.1051/JPHYSLET:019850046014064300","DOIUrl":"https://doi.org/10.1051/JPHYSLET:019850046014064300","url":null,"abstract":"It is shown that the properties of the upper critical fields in organic superconductors can be understood in terms of pure TYPE II superconductivity. The experimental observation of high critical fields violating Clogston's criterion could give support in favour of triplet-paired superconductivity Etude theorique montrant que les valeurs des champs critiques superieurs peuvent s'interpreter dans le cadre de la theorie des supraconducteurs propres de type II. Possibilite d'existence du supraconduction avec couplage triplet si l'on observe des valeurs depassant la limite de Clogston","PeriodicalId":14822,"journal":{"name":"Journal De Physique Lettres","volume":"111 1","pages":"643-646"},"PeriodicalIF":0.0,"publicationDate":"1985-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82350072","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 : 1985-07-01DOI: 10.1051/JPHYSLET:019850046013061700
J. Bonnet, M. Boissier, J. Pelous, R. Vacher, Pl. E. Bataillon, Montpellier Cédex, France M. Descamps, J. L. Sauvajol
The elastic constants of cyanoadamantane have been measured in the plastic and «glassy» crystal phases. A special attention has been given to the temperature evolution of C 11 as well as to the damping of the corresponding mode. Comparison with neutron results shows a strong dispersion at room temperature. The temperature dependence of C 11 in the plastic phase has been explained by the setting-up of a local antiferro ordering of molecules Determination des constantes d'elasticite d'apres les mesures de diffusion Brillouin sur monocristal entre 80 et 435 K. Variation thermique de C 11 et attenuation du mode correspondant. Comparaison aux donnees de diffusion de neutrons: existence d'une forte dispersion a temperature ambiante. Explication de la variation thermique de C 11 en phase plastique par apparition d'un ordre moleculaire local de type antiferro
{"title":"« Glassy » and plastic crystals of cyanoadamantane : a Brillouin scattering investigation","authors":"J. Bonnet, M. Boissier, J. Pelous, R. Vacher, Pl. E. Bataillon, Montpellier Cédex, France M. Descamps, J. L. Sauvajol","doi":"10.1051/JPHYSLET:019850046013061700","DOIUrl":"https://doi.org/10.1051/JPHYSLET:019850046013061700","url":null,"abstract":"The elastic constants of cyanoadamantane have been measured in the plastic and «glassy» crystal phases. A special attention has been given to the temperature evolution of C 11 as well as to the damping of the corresponding mode. Comparison with neutron results shows a strong dispersion at room temperature. The temperature dependence of C 11 in the plastic phase has been explained by the setting-up of a local antiferro ordering of molecules Determination des constantes d'elasticite d'apres les mesures de diffusion Brillouin sur monocristal entre 80 et 435 K. Variation thermique de C 11 et attenuation du mode correspondant. Comparaison aux donnees de diffusion de neutrons: existence d'une forte dispersion a temperature ambiante. Explication de la variation thermique de C 11 en phase plastique par apparition d'un ordre moleculaire local de type antiferro","PeriodicalId":14822,"journal":{"name":"Journal De Physique Lettres","volume":"17 1","pages":"617-621"},"PeriodicalIF":0.0,"publicationDate":"1985-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86156448","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 : 1985-06-01DOI: 10.1051/JPHYSLET:019850046012056900
C. Marcenat, A. Benoît, A. Briggs, C. Arzoumanian, A. D. Goër, F. Holtzberg
Measurements of the specific heat C(T) of a spin glass Eu 0.44 Sr 0.56 S single crystal have been performed between 0.7 and 10 K, and with applied magnetic fields (H=0, 4, 6 and 7 T). The application of a large magnetic field strongly modifies the C(T) behaviour, with a large decrease at low temperatures: the quasilinear variation observed in zero field is replaced by an exponential variation characteristic of the opening of a gap in the excitation spectrum. These results, together with those of magneto-thermal resistivity obtained previously, can be described with the assumption of two kinds of magnetic excitations: (i) very low energy collective excitations and (ii) single spin excitation of Eu 2+ ions in the external magnetic field augmented by some internal field of 3.2 T, the origin of which is discussed Mesures de chaleur massique sur un monocristal de verre de spin isolant Eu 0,44 Sr 0,56 S entre 0,7 et 10 K, sous champ magnetique H(0 a 7 T): effet important du champ dur C(T) avec une tres forte diminution a basse temperature, la variation quasi lineaire en champ nul etant remplacee par une variation exponentielle, caracteristique de l'apparition d'une bande interdite dans le spectre des excitations. A l'aide de resultats anterieurs sur la conductivite thermique en champ magnetique, interpretation par deux types d'excitations magnetiques: collectives et d'ions Eu 2+
在0.7到10 K之间，外加磁场(H= 0,4,6和7 T)，测量了自旋玻璃Eu 0.44 Sr 0.56 S单晶的比热C(T)。大磁场的应用强烈地改变了C(T)行为，在低温下大幅度降低:在零场中观察到的拟线性变化被激发光谱中间隙打开的指数变化特征所取代。这些结果，连同之前得到的磁热电阻率，可以用两种磁激励的假设来描述:(i)极低能量的集体激发和(ii) Eu 2+离子在外部磁场中被一些3.2 T的内部磁场增强的单自旋激发，讨论了其起源。测量de chaleur massique sur un单晶自旋隔离体Eu 0,44 Sr 0,56 S中心0,7 et 10 K, sous champ magnetique H(0 a 7 T):影响重要的du champ dur C(T)平均为基础温度的降低，la变化准线性的en champ nuetant取代了par变化指数，l'apparition d'une波段间的特征与光谱激发无关。A 'aide de resultsterieurs sur la传导热学在champ magnetique，解释双类型激发态磁学:集体与离子Eu 2+
{"title":"Magnetic excitations of a Heisenberg spin glass : evidence for a gap in high magnetic fields","authors":"C. Marcenat, A. Benoît, A. Briggs, C. Arzoumanian, A. D. Goër, F. Holtzberg","doi":"10.1051/JPHYSLET:019850046012056900","DOIUrl":"https://doi.org/10.1051/JPHYSLET:019850046012056900","url":null,"abstract":"Measurements of the specific heat C(T) of a spin glass Eu 0.44 Sr 0.56 S single crystal have been performed between 0.7 and 10 K, and with applied magnetic fields (H=0, 4, 6 and 7 T). The application of a large magnetic field strongly modifies the C(T) behaviour, with a large decrease at low temperatures: the quasilinear variation observed in zero field is replaced by an exponential variation characteristic of the opening of a gap in the excitation spectrum. These results, together with those of magneto-thermal resistivity obtained previously, can be described with the assumption of two kinds of magnetic excitations: (i) very low energy collective excitations and (ii) single spin excitation of Eu 2+ ions in the external magnetic field augmented by some internal field of 3.2 T, the origin of which is discussed Mesures de chaleur massique sur un monocristal de verre de spin isolant Eu 0,44 Sr 0,56 S entre 0,7 et 10 K, sous champ magnetique H(0 a 7 T): effet important du champ dur C(T) avec une tres forte diminution a basse temperature, la variation quasi lineaire en champ nul etant remplacee par une variation exponentielle, caracteristique de l'apparition d'une bande interdite dans le spectre des excitations. A l'aide de resultats anterieurs sur la conductivite thermique en champ magnetique, interpretation par deux types d'excitations magnetiques: collectives et d'ions Eu 2+","PeriodicalId":14822,"journal":{"name":"Journal De Physique Lettres","volume":"24 1","pages":"569-574"},"PeriodicalIF":0.0,"publicationDate":"1985-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76543139","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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