Interference Effects on Kondo-Assisted Transport through Double Quantum Dots

We systematically investigate electron transport through double quantum dots with particular emphasis on interference induced via multiple paths of electron propagation. By means of the slave-boson mean-field approximation, we calculate the conductance, the local density of states, the transmission probability in the Kondo regime at zero temperature. It is clarified how the Kondo-assisted transport changes its properties when the system is continuously changed among the serial, parallel and T-shaped double dots. The obtained results for the conductance are explained in terms of the Kondo resonances influenced by interference effects. We also discuss the impacts due to the spin-polarization of ferromagnetic leads.Comment: 9 pages, 11 figures ; minor corrections and references adde

Low energy electronic states and triplet pairing in layered cobaltates

The structure of the low-energy electronic states in layered cobaltates is considered starting from the Mott insulating limit. We argue that the coherent part of the wave-functions and the Fermi-surface topology at low doping are strongly influenced by spin-orbit coupling of the correlated electrons on the $t_{2g}$ level. An effective t-J model based on mixed spin-orbital states is radically different from that for the cuprates, and supports unconventional, pseudospin-triplet pairing.Comment: 4 pages, 3 figure

Strong parity mixing in the FFLO superconductivity in systems with coexisting spin and charge fluctuations

We study the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state of spin fluctuation mediated pairing, and focus on the effect of coexisting charge fluctuations. We find that (i) consecutive transitions from singlet pairing to FFLO and further to $S_z=1$ triplet pairing can generally take place upon increasing the magnetic field when strong charge fluctuations coexist with spin fluctuations, and (ii) the enhancement of the charge fluctuations lead to a significant increase of the parity mixing in the FFLO state, where the triplet/singlet component ratio in the gap function can be close to unity. We propose that such consecutive pairing state transition and strong parity mixing in the FFLO state may take place in a quasi-one-dimensional organic superconductor (TMTSF)$_2X$.Comment: 5 pages, 5 figures. To be published in Phys. Rev. Let

GMC Collisions as Triggers of Star Formation. V. Observational Signatures

We present calculations of molecular, atomic and ionic line emission from simulations of giant molecular cloud (GMC) collisions. We post-process snapshots of the magneto-hydrodynamical simulations presented in an earlier paper in this series by Wu et al. (2017) of colliding and non-colliding GMCs. Using photodissociation region (PDR) chemistry and radiative transfer we calculate the level populations and emission properties of $^{12}$CO $J=1-0$, [CI] $^3{\rm P}_1\rightarrow{^3{\rm P}}_0$ at $609\,\mu$m, [CII] $158\,\mu$m and [OI] $^3{\rm P}_1\rightarrow{^3{\rm P}}_0$ transition at $63\,\mu$m. From integrated intensity emission maps and position-velocity diagrams, we find that fine-structure lines, particularly the [CII] $158\,\mu$m, can be used as a diagnostic tracer for cloud-cloud collision activity. These results hold even in more evolved systems in which the collision signature in molecular lines has been diminished.Comment: 10 pages, 7 figures, accepted for publication in ApJ, comments welcom

A Novel Multi-parameter Family of Quantum Systems with Partially Broken N-fold Supersymmetry

We develop a systematic algorithm for constructing an N-fold supersymmetric system from a given vector space invariant under one of the supercharges. Applying this algorithm to spaces of monomials, we construct a new multi-parameter family of N-fold supersymmetric models, which shall be referred to as "type C". We investigate various aspects of these type C models in detail. It turns out that in certain cases these systems exhibit a novel phenomenon, namely, partial breaking of N-fold supersymmetry.Comment: RevTeX 4, 28 pages, no figure

Specific-heat evidence for strong electron correlations in the thermoelectric material (Na,Ca)Co_{2}O_{4}

The specific heat of (Na,Ca)Co_{2}O_{4} is measured at low-temperatures to determine the magnitude of the electronic specific-heat coefficient \gamma, in an attempt to gain an insight into the origin of the unusually large thermoelectric power of this compound. It is found that \gamma is as large as 48 mJ/molK^2, which is an order of magnitude larger than \gamma of simple metals. This indicates that (Na,Ca)Co_{2}O_{4} is a strongly-correlated electron system, where the strong correlation probably comes from the low-dimensionality and the frustrated spin structure. We discuss how the large thermopower and its dependence on Ca doping can be understood with the strong electron correlations.Comment: 5 pages, 4 figures, accepted for publication in Phys. Rev.

Tunnelling spectroscopy of the interface between Sr2RuO4 and a single Ru micro-inclusion in eutectic crystals

The understanding of the zero bias conductance peak (ZBCP) in the tunnelling spectra of S/N junctions involving d-wave cuprate superconductors has been important in the determination of the phase structure of the superconducting order parameter. In this context, the involvement of a p-wave superconductor such as Sr2RuO4 in tunnelling studies is indeed of great importance. We have recently succeeded in fabricating devices that enable S/N junctions forming at interfaces between Sr2RuO4 and Ru micro-inclusions in eutectic crystals to be investigated.3 We have observed a ZBCP and have interpreted it as due to the Andreev bound state, commonly seen in unconventional superconductors. Also we have proposed that the onset of the ZBCP may be used to delineate the phase boundary for the onset of a time reversal symmetry broken (TRSB) state within the superconducting state, which does not always coincide with the onset of the superconducting state. However, these measurements always involved two interfaces between Sr2RuO4 and Ru. In the present study, we have extended the previous measurements to obtain a deeper insight into the properties of a single interface between Sr2RuO4 and Ru.Comment: To appear in J. Phys. Soc. Jpn. Vol. 75 No.12 issu

Theory of pairing symmetry inside the Abrikosov vortex core

We show that the Cooper pair wave function at the center of an Abrikosov vortex with vorticity m has different parity with respect to frequency from that in the bulk if m is an odd number and has the same parity if m is an even number. As a result, in a conventional vortex with m=1, the local density of states at the Fermi energy has a maximum (minimum) at the center of the vortex core in even(odd)-frequency superconductor. We propose a scanning tunneling microscope experiment using a superconducting tip to explore odd-frequency superconductivity.Comment: 5 pages, 3 figure

Kummiluokkatoiminnan arviointi

Tämän opinnäytetyön tarkoituksena oli kuvata ja arvioida kummiluokkatoimintaa ja sen vaikutuksia sairaanhoitajaopiskelijan/terveydenhoitajaopiskelijan opintoihin sekä työelämään pääsemiseen ja sopeutumiseen. Tämä opinnäytetyö toteutettiin empiirisenä tutkimuksena. Kummiluokkatoimintaa arvioitiin kyselyn avulla. Kysely tehtiin sähköisenä Webropol-kyselynä. Kysely lähetettiin sähköpostitse 55 hoitoalan opiskelijalle, jotka olivat olleet mukana kummiluokkatoiminnassa. Kyselyyn vastasi yhdeksän opiskelijaa, vastausprosentti oli 16,36 %. Kysely sisälsi sekä avoimia kysymyksiä että monivalintakysymyksiä. Vastausten analysointiin käytettiin sisällönanalyysiä sekä tilastointia. Kyselyn tulokseksi saatiin, että opiskelijat eivät pääosin olleet tyytyväisiä kummiluokkatoimintaan sellaisena kuin se oli toteutunut. Kummiluokkatapaamisia oli ollut liian vähän, eikä niillä ollut vaikutusta työn saantiin. Kuitenkin se toiminta, mitä opiskelijoille oli tarjottu, oli mieleistä. Muutaman opiskelijan mielestä toiminta oli lisännyt halua työskennellä Varsinais-Suomen sairaanhoitopiirissä ja yhden mielestä se oli tehnyt työnhausta helpompaa. Myös vierailukäynnit ja esitykset olivat olleet kiinnostavia, niitä olisi vain pitänyt olla enemmän. Tämän opinnäytetyön tuomaa tietoa voidaan käyttää kummiluokkatoiminnan kehittämiseen, jotta hoitoalan opiskelijat saadaan yhä enemmän sitoutumaan ja kiinnostumaan tulevasta ammatistaan. Saadut tulokset antavat myös lisää syitä kummiluokkatoiminnan jatkamiselle. Jatkotutkimuksina voisi selvittää, miten kummiluokkatoiminta vaikuttaa Turun Yliopistolliseen sairaalaan ja VSSHP:in, eli hyötyykö toiminnasta opiskelijoiden lisäksi myös organisaatio.The purpose of this study was to describe and evaluate the godparent activities and its effects on nursing studies, as well as to work to reach and adjust. This thesis has been implemented by empirical research. Godparent activity was assessed using an inquiry. The inquiry was conducted by Webropol survey. The inquiry was sent by e-mail of 55 nursing students, who had been involved in godparent activities. Nine students responded to the inquiry, the response rate was 16.36%. The inquiry contained both open questions and multiple choice questions. Content analysis and statistics were used for the analysis of the responses. The inquiry led to the result that students are not generally been satisfied with the godparent activities as it had been. Godparent meetings were only few, nor did they have the effect of employment. However, it is low, what activities were offered to students was worthwhile. A few view, the activities had added desire to work in Hospital District of Southwest Finland, and one thought it was done work search easier. Also, visits and information lectures were interesting; they would only have been more. This thesis can be used to develop the godparent activities, to get nursing students to increasingly commit to and interested in their future profession. The information obtained will also provide more reasons to continuation of godparent activities. Possible further studies could figure out how godparent activities affect the Turku University Hospital and in Hospital District of Southwest Finland, to benefit for the students, but also the organization

The effect of interchain interaction on the pairing symmetry competition in organic superconductors (TMTSF)2_2X

We investigate the effect of interchain repulsive interaction on the pairing symmetry competition in quasi-one-dimensional organic superconductors (TMTSF)$_2$X by applying random phase approximation and quantum Monte Carlo calculation to an extended Hubbard model. We find that interchain repulsive interaction enhances the $2k_F$ charge fluctuations, thereby making the possibility of spin-triplet $f$-wave pairing dominating over spin-singlet d-wave pairing realistic.Comment: 4 page