Analysis of S-d Exchange Interactions in Dilute Cu-mn Alloys

Analysis of S-d Exchange Interactions in Dilute Cu-mn AlloysPhenomenological analysis of the s-d trade fundamental interactions in dilute Cu-Mn alloys at helium temperaturesAL-Jalali, M. A.AbstractThe S-d exchange interactions in dilute Cu-Mn alloys was studied on concentration ( C ) varying amongst 10.5 and 2081.8 ppm of Mn in Cu within the ( 0.03K 4.2K ) temperature range. Using electrical electric resistance data on those alloys, the s-d exchange integral ( Jsd ), which is negative, has reckon to show a take up dependence on (Ln C). This dependence, confirming thus the dominance of Kondo effect at a lower key hundred0 ppm dross concentration, but above this concentration, we expected an interference between Kondo effect and spin glass government activity, which mean that spin glass regime has to restrain more than Kondo effect. Keywords s-d interaction electrical impedance Jsd Kondo effect spin glass. PACS 75 50, 7510, 75 40, 75 30.IntroductionThe main objective of thi s paper is to read the huge effects on the coupling between the dilute magnetic impurities (Mn), which gives rise to the formation of local magnetic moments, and the conduction electrons from the host noble metal (Cu).Electrical resistivity is a great source of information, especially to get the values of the s-d exchange integral Jsd .For a very dilute alloys (concentration below 100 ppm of Mn), the low-temperature resistivity is dominated by an anomalous Kondo scattering of the conduction electron spin at the local magnetic moments. A typical logarithmic leaving of the resistivity will begin above the Kondos temperature( TK ) until the minimum in the resistivity of Cu-Mn Kondo alloys, where higher temperatures is prevailed, and when the magnetic impurity concentrationIncreasing until ( 1 at. %), the interaction between the local magnetic moments and conduction electrons ,which is governed by the Ruderman-Kittel-Kasuya-Yosida (RKKY) 1,2,3 interaction will form a spin-glass phase 4.The method, I have used, to calculate Jsd was the analysis of jumpy experimental data and by simi-emperical simple calculating, I found that the Jsd decreases logarithmically with concentration and gives a very important information about contest between Kondo effect and spin glass regime5, which need a deeper study in the future.Theoretical backgroundThe introduction of few ppm of 3d or 4f magnetic impurity in a non-magnetic matrix leads to an s d exchange interaction between the spins of the conduction electrons Se and the Localized magnetic moment Sd of the transition element, which provide be described by a HamiltonianWhere (Jsd) is the exchange coupling parameter, and is any ordinary scattering from the ion carrying the local moment. With a negative Jsd, the interaction leads to an increase of place spin disorder resistivity with decreasing temperature.The competition between the spin disorder scattering and the phonon exhibits the minimum in the resistivity of this reg ime 6, 7, 8, 9. Phenomenologically the above competition is mainly manifested at low temperatures in the formWhere the spin scattering resistivity, and, ( EF =the Fermi energy),(Z=number of conduction electrons per atom).In this work, I endeavour to show the conduct of Jsd in some Cu Mn alloys, despite the fact that there is the bulk of information has been put forward on these alloys during and after the 1980s, the electrical resistivity one of many sources to provide a powerful means to trace the s d exchange interaction dominating these alloys.Analysis of dataMatula and others report crude data 10, 11, 12 on electrical resistivity and methods of manufacturing of alloys, especially in respect of purity, constituting the major experimental background in this work. They come from direct measurements already carried on Cu Mn alloys (and many others noble transition metals alloys) with concentrations ranging from 10.5 ppm to 2081.3 ppm of Mn in Cu within the ( 0.03 4.2K ) range 1 1, 12,13 .Figure (1) scales versus Ln (T/c) give us by suit fitting an expression like a logarithm of power series solutionThe first two terms (first- order approximation) show a bold line at figure (1), where pure magnetic resistivity could be defined from that lines as a function of ( LnT), and by using a fittings programming we can find from the ones of the bold lines a relation as following (figure(2)) -This matches with Hamanns expression 13, 14, 15, and 16 Tk =Kondo temperatureFigure (2) expresses exactly what a compatible between experimental relation (4) and theoretical Hamanns expression (5) there are.Definitely, allowing the inclusion of potential scattering effect with single impurity kondo effect, and nipping determination of kondo temperature Tk = 36 mK. Calculated values of Jsd reveal a variation(C is Mns concentration in ppm units), as it has shown in figure (3).Expression ( 6 ) was calculated according to a width of internal field distribution 12,16 at Tmax ( cha racterize the maximum value of the resistivity at figure(1)(7)Results and discussionAs it is shown in figure ( 3 ), above 850 ppm, our calculation to Jsd leads, just as other works do 12,17 , 18 , 19, 20 to believe that magnetic transformation takes place from antiferromagnetic to ferromagnetic state and between 860 ppm and 2000 ppm may be a spin glass regime starts to prevail.When we come back to Kondos temperature at Hamanns expression (5), it is most appropriately to denote that the Kondos temperature given as 21Where, initially, TF =8.12 104 k, and n (EF) =0.294 ev-1.It seems that Tk is not constant as we noted above, and is not consistent with 22, And has clear dependence on Jsd . Of course, we need more studying to pursue this point.Finally, as a instead of conclusion put (Result), and from figure (3), we can classify a Kondos regime in respect of concentration as followingpure kondo regime vanishes at concentration 63 ppm of magnetic impurity (Mn) .Mixed regime ( kondo + SG ) from 63 ppm to 860 ppm.Ideal spin glass from 860 ppm to about 1%.ConclusionWhen we increase the concentration of magnetic impurity, The s-d exchange interactions will move to RKKY interactions, where Jsd will represent a phenomenological order parameter, which reflects a shift of interactions between conduction electrons and localized magnetic moments and discovers the new magnetic transformation from a regime to be other.1