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Université de Fribourg

Revealing the pseudogap in ${\mathrm{Sr}}_{3}{({\mathrm{Ru}}_{0.985}{\mathrm{Fe}}_{0.015})}_{2}{\mathrm{O}}_{7}$ by optical spectroscopy

Ban, W. J. ; Xu, Bing ; Li, W. H. ; Wang, Y. ; Ge, J. J. ; Li, P. G. ; Yang, R. ; Dai, Y. M. ; Mao, Z. Q. ; Xiao, H.

In: Physical Review B, 2018, vol. 98, no. 20, p. 205111

We report resistivity, magnetization, and optical spectroscopy study on single-crystal sample of Sr3(Ru0.985Fe0.015 )2O7. An upturn is observed in resistivity at about 30 K. Below 30 K, the dip in resistivity R(ω), the suppression in scattering rate 1/τ (ω), the peaklike feature in optical conductivity σ1(ω), and the remainder of spectral weight all suggest the formation of a pseudogap....

Université de Fribourg

Spin-freezing and the Sachdev-Ye model

Werner, Philipp ; Kim, Aaram J. ; Hoshino, Shintaro

In: EPL (Europhysics Letters), 2018, vol. 124, no. 5, p. 57002

Spin-freezing is the origin of bad-metal physics and non-Fermi liquid (non-FL) properties in a broad range of correlated compounds. In a multi-orbital lattice system with Hund coupling, doping of the half-filled Mott insulator results in a highly incoherent metal with frozen magnetic moments. These moments fluctuate and collapse in a crossover region that is characterized by unusual non-Fermi...

Université de Fribourg

Coupled Cu and Mn charge and orbital orders in YBa₂Cu₃O₇/Nd 0.65 (Ca 1-y Sr y ) 0.35 MnO₃ multilayers

Perret, Edith ; Monney, Claude ; Johnston, S. ; Khmaladze, Jarji ; Lyzwa, Fryderyk ; Gaina, Roxana ; Dantz, M. ; Pelliciari, Jonathan ; Piamonteze, C. ; Mallett, B.P.P. ; Minola, M. ; Keimer, B. ; Schmitt, Thorsten ; Bernhard, Christian

In: Communications Physics, 2018, vol. 1, no. 1, p. 45

The observation of a charge density wave in the underdoped cuprate high Tc superconductors (Cu-CDW) raised a debate about its relationship with superconductivity. In bulk YBa2Cu3O7−δ the Cu-CDW is incipient and mainly pinned by defects. Nevertheless, a large magnetic field can induce a true long-range Cu- CDW order as it suppresses superconductivity. An enhanced Cu-CDW order was also ...

Université de Fribourg

Comparative feeding rates of native and invasive ascidians

Hoxha, Tedi ; Crookes, Steve ; Lejeusne, Christophe ; Dick, Jaimie T.A. ; Chang, Xuexiu ; Bouchemousse, Sarah ; N.Cuthbert, Ross ; Isaac, Hugh J.Mac

In: Marine Pollution Bulletin, 2018, vol. 135, p. 1067–1071

Ascidians have a recent history of species introductions globally, often with strong ecological impacts. Comparisons of per capita effects of invaders and comparable natives are useful to assess such impacts. Here, we explore ingestion rates (IR) and clearance rates (CR) of Ciona intestinalis and Ciona robusta, co-occurring native and non-native ascidians, respectively, from Brittany, France....

Université de Neuchâtel

Ramsey spectroscopy in a Rubidium vapor cell and realization of an ultra-stable atomic clock

Gharavipour, Mohammadreza ; Mileti, Gaetano (Dir.)

Thèse de doctorat : Université de Neuchâtel, 2018.

Divers domaines d’application dans l’industrie, les télécommunications, la navigation et l’espace exigent des étalons de fréquence fiables, compacts et performants avec un niveau de stabilité de −14 à 105s (équivalent à <1 ns/jour). Avec la technologie des lasers à semi-conducteurs, la technique du pompage optique par laser a ouvert de nouveaux...

Université de Fribourg

Metallic contact between MoS2 and Ni via Au nanoglue

Shi, Xinying ; Posysaev, Sergei ; Huttula, Marko ; Pankratov, Vladimir ; Hoszowska, Joanna ; Dousse, Jean?Claude ; Zeeshan, Faisal ; Niu, Yuran ; Zakharov, Alexei ; Li, Taohai ; Miroshnichenko, Olga ; Zhang, Meng ; Wang, Xiao ; Huang, Zhongjia ; Saukko, Sami ; González, Diego López ; Dijken, Sebastiaan van ; Alatalo, Matti ; Cao, Wei

In: Small, 2018, vol. 14, no. 22, p. 1704526

A critical factor for electronics based on inorganic layered crystals stems from the electrical contact mode between the semiconducting crystals and the metal counterparts in the electric circuit. Here, a materials tailoring strategy via nanocomposite decoration is carried out to reach metallic contact between MoS2 matrix and transition metal nanoparticles. Nickel nanoparticles (NiNPs) are ...

Université de Fribourg

Optical study of Dirac fermions and related phonon anomalies in the antiferromagnetic compound CaFeAsF

Xu, B. ; Xiao, H. ; Gao, B. ; Ma, Y. H. ; Mu, G. ; Mar?ík, Premysl ; Sheveleva, Evgeniia ; Lyzwa, F. ; Dai, Y. M. ; Lobo, R. P. S. M. ; Bernhard, Christian

In: Physical Review B, 2018, vol. 97, no. 19, p. 195110

We performed optical studies on CaFeAsF single crystals, a parent compound of the 1111-type iron-based superconductors that undergoes a structural phase transition from tetragonal to orthorhombic at Ts=121 K and a magnetic one to a spin density wave (SDW) state at TN=110 K. In the low-temperature optical conductivity spectrum, after the subtraction of a narrow Drude peak, we observe a...

Université de Fribourg

Lattice-mediated magnetic order melting in ${\mathrm{TbMnO}}_{3}$

Baldini, Edoardo ; Kubacka, Teresa ; Mallett, Benjamin P. P. ; Ma, Chao ; Koohpayeh, Seyed M. ; Zhu, Yimei ; Bernhard, Christian ; Johnson, Steven L. ; Carbone, Fabrizio

In: Physical Review B, 2018, vol. 97, no. 12, p. 125149

Recent ultrafast magnetic-sensitive measurements [Johnson et al., Phys. Rev. B 92, 184429 (2015); Bothschafter et al., Phys. Rev. B 96, 184414 (2017)] have revealed a delayed melting of the long-range cycloid spin order in TbMnO3 following photoexcitation across the fundamental Mott-Hubbard gap. The microscopic mechanism behind this slow transfer of energy from the photoexcited carriers to...

Consortium of Swiss Academic Libraries

Percolation limited magnetic order in Eu1-xCaxB6

Wigger, G. A. ; Felder, E. ; Weller, M. ; Streule, S. ; Ott, H. R. ; Bianchi, A. D. ; Fisk, Z.

In: The European Physical Journal B - Condensed Matter and Complex Systems, 2005, vol. 46, no. 2, p. 231-235