Mechanism of metallization and superconductivity suppression in YBa2(_2(Cu0.97_{0.97}Zn0.03)3_{0.03})_3O6.92_{6.92} revealed by 67^{67}Zn NQR

We measure the nuclear quadrupole resonance (NQR) signal on the Zn site in nearly optimally doped YBa$_2$Cu$_3$O$_{6.92}$, when Cu is substituted by 3\% of isotopically pure $^{67}$Zn. We observe that Zn creates large insulating islands, confirming two earlier conjectures: that doping provokes an orbital transition in the CuO$_2$ plane, which is locally reversed by Zn substitution, and that the islands are antiferromagnetic. Also, we find that the Zn impurity locally induces a breaking of the D$_4$ symmetry. Cluster and DFT calculations show that the D$_4$ symmetry breaking is due to the same partial lifting of degeneracy of the nearest-neighbor oxygen sites as in the LTT transition in La$_{2-x}$Ba$_x$CuO$_4$, similarly well-known to strongly suppress superconductivity. These results show that in-plane oxygen $2p^5$ orbital configurations are principally involved in the metallicity and superconductivity of all high-T$_c$ cuprates, and provide a qualitative symmetry-based constraint on the SC mechanism.Comment: extended version, to appear in New Journal of Physic

Cu nuclear magnetic resonance study of charge and spin stripe order in La1.875_{1.875}Ba0.125_{0.125}CuO4_4

We present a Cu nuclear magnetic/quadrupole resonance study of the charge stripe ordered phase of LBCO, with detection of previously unobserved ('wiped-out') signal. We show that spin-spin and spin-lattice relaxation rates are strongly enhanced in the charge ordered phase, explaining the apparent signal decrease in earlier investigations. The enhancement is caused by magnetic, rather than charge fluctuations, conclusively confirming the long-suspected assumption that spin fluctuations are responsible for the wipeout effect. Observation of the full Cu signal enables insight into the spin and charge dynamics of the stripe-ordered phase, and measurements in external magnetic fields provide information on the nature and suppression of spin fluctuations associated with charge order. We find glassy spin dynamics, in agreement with previous work, and incommensurate static charge order with charge modulation amplitude similar to other cuprate compounds, suggesting that the amplitude of charge stripes is universal in the cuprates.Comment: 7 pages, 5 figure

Effective microwave conductivity and magnetoresistance in the mixed state of type-ii superconductors

An effective microwave conductivity is derived for the case of type-II superconductors in the mixed state. The ensuing expression for the microwave magnetoresistance predicts a nonlinear behaviour in agreement with the experiments

Magnetotransport of lanthanum doped RuSr2GdCu2O8 - the role of gadolinium

Strongly underdoped RuSr_1.9La_0.1GdCu_2O_8 has been comprehensively studied by dc magnetization, microwave measurements, magnetoresistivity and Hall resistivity in fields up to 9 T and temperatures down to 1.75 K. Electron doping by La reduces the hole concentration in the CuO2 planes and completely suppresses superconductivity. Microwave absorption, dc resistivity and ordinary Hall effect data indicate that the carrier concentration is reduced and a semiconductor-like temperature dependence is observed. Two magnetic ordering transitions are observed. The ruthenium sublattice orders antiferromagnetically at 155 K for low applied magnetic field and the gadolinium sublattice antiferromagnetically orders at 2.8 K. The magnetoresistivity exhibits a complicated temperature dependence due to the combination of the two magnetic orderings and spin fluctuations. It is shown that the ruthenium magnetism influences the conductivity in the RuO2 layers while the gadolinium magnetism influences the conductivity in the CuO2 layers. The magnetoresistivity is isotropic above 4 K, but it becomes anisotropic when gadolinium orders antiferromagnetically.Comment: 7 pages, 9 figures, submitted to European Physical Journal

Opažanje Josephsonovog efekta putem mikrovalne apsorpcije u visokotemperaturnim supravodičima

Supravodljivost već gotovo osam desetljeća izaziva veliko zanimanje fizičara. Značaj same pojave supravodljivosti u praktičnim primjenama toliko je velik da ga nije potrebno posebno naglašavati. S druge strane, teorijsko objašnjenje pojave veliki je trijumf mehanike, teorije koja ja potpuno izmjenila fiziku dvadesetog stoljeća. Nastojanja da se načine supravodiči što viših temperatura prijelaza i što većih kritičnih struja i magnetskih polja nisu prestala do današnjih dana. Razvoj fizike počeo je otkrićem supravodljivosti 1911. godine. To područje istraživanja imalo je nekoliko velikih uzleta u svom razvoju: 1933. godine otkriven je Meissnerov efekt, 1950. predviđen je i otkriven izotopni efekt, iste godine dana je vrlo dobra fenomenološka teorija supravodljivosti, a 1957. razvijena je BCS teorija - potpuna mikroskopska teorija supravodljivosti. Jedan isto tako veliki uzlet fizike supravodiča zbio se u toku 1987. godine. Još krajem 1986. nađeni su keramički materijali koji su pokazivali svojstva supravodljivosti. Temperature prijelaza tih materijala bile su više od svih do tada poznatih metalnih supravodiča. Već početkom 1987. materijali istog tipa dosegli su temperaturu supravodljivog prijelaza od oko 90 K. Kad je prekoračena granica od 77 K (vrelište dušika) otvoren je put istraživanjima supravodljivih uzoraka pomoću velikog broja relativno pristupačnih metoda. Jedna od vrlo osjetljivih metoda u fizici je ESR spektroskopija (elektronska spinska rezonancija). Mjeri se promjena apsorpcije mikro-valova promjenom vanjskog magnetskog polja. Kako su supravodiči novog tipa vrlo osjetljivi na promjene magnetskog polja, njihovo istraživanje pomoću spektrometra za ESR može dati vrlo korisne informacije o svojstvima tih materijala. U ovom radu pokazat ćemo kako se uređaj za elektronsku spinsku rezonanciju može iskoristiti u određivanju temperature prijelaza vrlo male količine materijala u supravodljivo stanje. Pokušat ćemo dati i zadovoljavajuće teorijska objašnjenje rezultata pomoću Josephsonovih efekata. Želja nam je, također, ukazati na neke mogućnosti daljnjeg istraživanja u području visokotemperaturnih supravodiča

Cooperative Mercury Motion in the Ionic Conductor Cu2HgI4

We present the observation of glasslike dynamic correlations of mobile mercury ions in the ionic conductor Cu_2HgI_4, detected in both NMR and nonlinear conductivity experiments. The results show that dynamic cooperativity appears in systems seemingly unrelated to glassy and soft arrested materials. A simple kinetic two-component model is proposed, which seems to provide a good description of the cooperative ionic dynamics

EMPLOYEE SATISFACTION IN GEODETSKI ZAVOD CELJE D.O.O.

Pomanjkanje zadovoljstva zaposlenih v delovnem okolju je značilnost mnogih organizacij in sistemov. S strokovnim pristopom in višjo organizacijsko kulturo je mogoče omiliti oziroma se izogniti razmeram, ki se kažejo v zmanjšanju učinkovitosti posameznikov. Želja vsakega dobrega vodje je ustvariti dobre delovne razmere in doseči odlične delovne rezultate. V uvodnem delu smo predstavili problem nezadovoljstva zaposlenih na Geodetskem zavodu Celje, d. o. o. (v nadaljevanju Geodetski zavod Celje ali GZC), pri projektu Kontrola subvencij in metode dela. Diplomska naloga obsega dva dela: teoretičnega in empiričnega. V teoretičnem delu smo uporabili metodo deskripcije in kompilacije, v empiričnem delu, kjer smo med zaposlenimi izvajali anketo, pa smo uporabili analitični pristop. Teoretični del je zasnovan na podlagi dostopne literature, s pomočjo katere opišemo zadovoljstvo zaposlenih, ter absentizem in fluktuacijo, ki sta lahko posledica nezadovoljstva zaposlenih. V empiričnem delu sledi predstavitev podjetja Geodetski zavod Celje ter raziskava s pomočjo anketnega vprašalnika, ki vključuje zaposlene v podjetju na projektu Kontrola subvencij, ki ga Geodetski zavod Celje izvaja od leta 2006. Podana je tudi interpretacija rezultatov z ugotovitvami in predlogi k izboljšavi obstoječega stanja.Many organisations and systems are marked by a lack of satisfaction of employees in their working environment. This situation, which results in the decreased efficiency of individuals, can be eased or even completely avoided by employing a professional approach coupled with an improved organisational culture. Creating proper conditions for work and achieving excellent business performance is what every good leader desires. In the introductory section, this paper presents the problem of employee dissatisfaction at Geodetski zavod Celje d.o.o. in relation to the subsidy supervision project and the methods of work. This diploma thesis encompasses two parts: the theoretical and the empirical. In the theoretical part, we applied the method of description and compilation while in the empirical part we utilised an analytical approach and conducted a survey among the employees. The available literature served as the basis for the theoretical part that describes employee satisfaction, including absenteeism and fluctuation, which are both possible consequences of employee dissatisfaction. The empirical part presents the company, Geodetski zavod Celje d.o.o., and the questionnaire-based research that included the company employees working on the subsidy supervision project, which the company has been running since 2006. An interpretation of the results is provided along with findings and proposals for improving the existing situation

»ČISTO VSEENO JE, ALI JE PLESALEC NA VOZIČKU ALI NE, SAJ USTVARJAM UMETNOST«. Intervju z učiteljem inkluzivne plesne skupine o učenju plesa na invalidskem vozičku

Douglas Scott je plesalec, koreograf, pedagog in umetniški vodja, ki že več kot 25 let živi in dela v Atlanti v Georgii. Dolga leta je plesal s plesno skupino Ruth Mitchell ter hkrati delal kot plesni pedagog in koreograf. Leta 1991 je ustanovil inkluzivno plesno skupino, ki se danes imenuje Full Radius Dance in je ena redkih profesionalnih plesnih skupin te vrste v ZDA. Z inkluzivnim plesom, ki se takrat še ni imenoval tako, se je srečal leta 1990, ko je bil kot plesni učitelj povabljen na plesne delavnice za marginalne skupine (zaporniki, osebe z invalidnostjo, socialno izključeni ...). Takrat ni bilo mentorjev ali plesnih učiteljev, ki bi mu lahko svetovali o delu s plesalci na invalidskih vozičkih ali s posebnimi potrebami, in se je tako učil hkrati, ko je delal z njimi. Ustvaril je številne avtorske projekte in postavil na oder celovečerne plesne programe s svojo skupino. Prepoznaven je po odlični tehniki in inovativnem slogu. Douglas Scott je prejemnik številnih ameriških nagrad, zadnja je iz leta 2014, Governor‘s Award for Arts & Humanities v državi Georgia