TY - JOUR AU - Geresdi, Attila AU - Halbritter, András Ernő AU - Csontos, Miklós AU - Csonka, Szabolcs AU - Mihály, György AU - Wojtowicz, T AU - Liu, X AU - Jankó, B AU - Furdyna, JK TI - Nanoscale spin polarization in the dilute magnetic semiconductor (In,Mn)Sb JF - PHYSICAL REVIEW B J2 - PHYS REV B VL - 77 PY - 2008 IS - 23 PG - 4 SN - 2469-9950 DO - 10.1103/PhysRevB.77.233304 UR - https://m2.mtmt.hu/api/publication/117118 ID - 117118 AB - Results of point-contact Andreev-reflection experiments on (In,Mn)Sb are presented and analyzed in terms of current models of charge conversion at a superconductor-ferromagnet interface. We investigate the influence of surface transparency, and study the crossover from ballistic to diffusive transport regime as contact size is varied. Application of a Nb tip to a (In,Mn)Sb sample with Curie temperature T-C of 5.4 K allowed the determination of spin polarization when the ferromagnetic phase-transition temperature is crossed. We find a striking difference between the temperature dependence of the local spin polarization and of the macroscopic magnetization, and demonstrate that nanoscale clusters with magnetization close to the saturated value are present even well above the magnetic phase-transition temperature. LA - English DB - MTMT ER - TY - JOUR AU - Kézsmárki, István AU - Tomioka, Y AU - Miyasaka, S AU - Demkó, László AU - Okimoto, Y AU - Tokura, Y TI - Optical phase diagram of perovskite-type colossal magnetoresistance manganites with near-half doping JF - PHYSICAL REVIEW B J2 - PHYS REV B VL - 77 PY - 2008 IS - 7 SN - 2469-9950 DO - 10.1103/PhysRevB.77.075117 UR - https://m2.mtmt.hu/api/publication/117115 ID - 117115 LA - English DB - MTMT ER - TY - JOUR AU - Halbritter, András Ernő AU - Csonka, Szabolcs AU - Makk, Péter AU - Mihály, György TI - Interaction of hydrogen with metallic nanojunctions JF - JOURNAL OF PHYSICS-CONFERENCE SERIES J2 - J PHYS CONF SER VL - 61 PY - 2007 IS - 1 SP - 214 EP - 218 PG - 5 SN - 1742-6588 DO - 10.1088/1742-6596/61/1/043 UR - https://m2.mtmt.hu/api/publication/2599305 ID - 2599305 N1 - Funding Agency and Grant Number: Hungarian research funds OTKA [F049330, TS049881] Funding text: This work has been supported by the Hungarian research funds OTKA F049330, TS049881. AB - We study the behavior of hydrogen molecules between atomic-sized metallic electrodes using the mechanically controllable break junction technique. We focus on the interaction H2 with monoatomic gold chains demonstrating the possibility of a hydrogen molecule being incorporated in the chain. We also show that niobium is strongly reactive with hydrogen, which enables molecular transport studies between superconducting electrodes. This opens the possibility for a full characterization of the transmission properties of molecular junctions with superconducting subgap structure measurements. LA - English DB - MTMT ER - TY - JOUR AU - Kézsmárki, István AU - Hanasaki, N AU - Watanabe, K AU - Iguchi, S AU - Taguchi, Y AU - Miyasaka, S AU - Tokura, Y TI - Variation of the charge dynamics in bandwidth- and filling-controlled metal-insulator transitions of pyrochlore-type molybdates JF - PHYSICAL REVIEW B J2 - PHYS REV B VL - 73 PY - 2006 IS - 12 SN - 2469-9950 DO - 10.1103/PhysRevB.73.125122 UR - https://m2.mtmt.hu/api/publication/2632125 ID - 2632125 AB - The systematics of the bandwidth- and filling-controlled metal-insulator transitions (MITs) have been investigated for R2Mo2O7 family (R=Nd, Sm, Eu, Gd, Dy, and Ho) by infrared spectroscopy. The substantial role of electron correlation in driving the MIT is verified. With changing the R ionic radius (r) or equivalently the one-electron bandwidth (W), the MIT occurs in a continuous manner at r(c)approximate to r(R=Gd). The T=0 K gap continuously vanishes as Delta proportional to(r(c)-r), while at the metallic side the linear decrease of Drude weight is followed toward r(c). In the metallic compounds, some of the infrared-active phonon modes show remarkably large Fano asymmetry correlating with the Drude weight. These Mo-O-Mo bending modes strongly couple to the conduction electrons via effective modulation of the bandwidth. Even for r less than or similar to r(c) a minimal level of hole doping closes the correlation gap, for example, the barely insulating Gd2Mo2O7 is turned to an incoherent metal by 5% partial substitution of Gd3+ with Ca2+. However, even on further doping no coherent electronic states are formed, indicating the role of the disorder-induced localization effect besides the dominant correlation effects. LA - English DB - MTMT ER - TY - JOUR AU - Kézsmárki, István AU - Mihály, György AU - Gaal, R AU - Barisic, N AU - Akrap, A AU - Berger, H AU - Forro, L AU - Homes, CC AU - Mihály, László TI - Separation of orbital contributions to the optical conductivity of BaVS3 JF - PHYSICAL REVIEW LETTERS J2 - PHYS REV LETT VL - 96 PY - 2006 IS - 18 PG - 4 SN - 0031-9007 DO - 10.1103/PhysRevLett.96.186402 UR - https://m2.mtmt.hu/api/publication/2111177 ID - 2111177 LA - English DB - MTMT ER - TY - JOUR AU - Kézsmárki, István AU - Shimizu, Y AU - Mihály, György AU - Tokura, Y AU - Kanoda, K AU - Saito, G TI - Depressed charge gap in the triangular-lattice Mott insulator kappa-(ET)(2)Cu-2(CN)(3) JF - PHYSICAL REVIEW B J2 - PHYS REV B VL - 74 PY - 2006 IS - 20 PG - 4 SN - 2469-9950 DO - 10.1103/PhysRevB.74.201101 UR - https://m2.mtmt.hu/api/publication/2111176 ID - 2111176 LA - English DB - MTMT ER - TY - JOUR AU - Csonka, Szabolcs AU - Halbritter, András Ernő AU - Mihály, György TI - Pulling gold nanowires with a hydrogen clamp: Strong interactions of hydrogen molecules with gold nanojunctions JF - PHYSICAL REVIEW B J2 - PHYS REV B VL - 73 PY - 2006 IS - 7 PG - 6 SN - 2469-9950 DO - 10.1103/PhysRevB.73.075405 UR - https://m2.mtmt.hu/api/publication/1090214 ID - 1090214 AB - In this paper an experimental study of the interaction of hydrogen molecules with gold nanowires is presented. Our results show that chains of Au atoms can also be pulled in hydrogen environment; however, in this case the conductance of the chain is strongly reduced compared to the perfect transmission of pure Au chains. The comparison of our experiments with recent theoretical prediction for the hydrogen welding of Au nanowires implies that a hydrogen molecule can even be incorporated in the gold nanocontact, and this hydrogen clamp is strong enough to pull a chain of gold atoms. LA - English DB - MTMT ER - TY - GEN AU - Barisic, N AU - Kézsmárki, István AU - Fazekas, Patrik AU - Mihály, György AU - Berger, H AU - Demkó, László AU - Forró, L TI - Quantum critical phase in BaVS3 PY - 2006 UR - https://m2.mtmt.hu/api/publication/1030637 ID - 1030637 LA - English DB - MTMT ER - TY - JOUR AU - Csontos, Miklós AU - Balogh, Sára Judit AU - Kaptás, Dénes AU - Kiss, László Ferenc AU - Kovács, András AU - Mihály, György TI - Magnetic and transport properties of Fe-Ag granular multilayers JF - PHYSICAL REVIEW B J2 - PHYS REV B VL - 73 PY - 2006 IS - 18 PG - 9 SN - 2469-9950 DO - 10.1103/PhysRevB.73.184412 UR - https://m2.mtmt.hu/api/publication/140524 ID - 140524 AB - Results of magnetization, magnetotransport, and Mossbauer spectroscopy measurements of sequentially evaporated Fe-Ag granular composites are presented. The strong magnetic scattering of the conduction electrons is reflected in the sublinear temperature dependence of the resistance and in the large negative magnetoresistance. The simultaneous analysis of the magnetic properties and the transport behavior suggests a bimodal grain size distribution. A detailed quantitative description of the unusual features observed in the transport properties is given. LA - English DB - MTMT ER - TY - JOUR AU - Csontos, Miklós AU - Wojtowicz, T AU - Liu, X AU - Dobrowolska, M AU - Janko, B AU - Furdyna, JK AU - Mihály, György TI - Magnetic scattering of spin polarized carriers in (In,Mn)Sb dilute magnetic semiconductor JF - PHYSICAL REVIEW LETTERS J2 - PHYS REV LETT VL - 95 PY - 2005 IS - 22 PG - 4 SN - 0031-9007 DO - 10.1103/PhysRevLett.95.227203 UR - https://m2.mtmt.hu/api/publication/2789080 ID - 2789080 N1 - Department of Physics, Budapest University of Technology and Economics, Hungarian Academy of Sciences, 1111 Budapest, Hungary Department of Physics, University of Notre Dame, Notre Dame, IN 46556, United States Institute of Physics, Polish Academy of Sciences, 02-668 Warsaw, Poland Cited By :55 Export Date: 16 February 2021 CODEN: PRLTA Correspondence Address: Csontos, M.; Department of Physics, , 1111 Budapest, Hungary Department of Physics, Budapest University of Technology and Economics, Hungarian Academy of Sciences, 1111 Budapest, Hungary Department of Physics, University of Notre Dame, Notre Dame, IN 46556, United States Institute of Physics, Polish Academy of Sciences, 02-668 Warsaw, Poland Cited By :55 Export Date: 3 May 2021 CODEN: PRLTA Correspondence Address: Csontos, M.; Department of Physics, , 1111 Budapest, Hungary AB - Magnetoresistance measurements on the magnetic semiconductor (In,Mn)Sb suggest that magnetic scattering in this material is dominated by isolated Mn2+ ions located outside the ferromagnetically ordered regions when the system is below T-c. A model is proposed, based on the p-d exchange between spin-polarized charge carriers and localized Mn2+ ions, which accounts for the observed behavior both below and above the ferromagnetic phase transition. The suggested picture is further verified by high-pressure experiments, in which the degree of magnetic interaction can be varied in a controlled way. LA - English DB - MTMT ER -