R. Blinc

University of Ljubljana, Lubliano, Ljubljana, Slovenia

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Publications (945)2773.12 Total impact

  • Journal of Molecular Structure 02/2013; 176(1-2):331-335. DOI:10.1016/0022-2860(88)80253-9 · 1.60 Impact Factor
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    ABSTRACT: The structural phase transitions between the intercalated and the non-intercalated phases of the layer structure compound n-decylammoniumchloride and n-hexylammoniumchloride have been studied via proton-14N and proton-35Cl nuclear quadrupole double resonance. The results have been related to an order-disorder model of the alkylammonium chains. The temperature dependence of the order parameters of the -NH3 head groups has been determined.
    Zeitschrift für Physik B Condensed Matter 02/2013; 69(2-3):379-384. DOI:10.1007/BF01307295
  • J Seliger, V Žagar, R Blinc
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    ABSTRACT: The temperature dependence of the 17O nuclear quadrupole double-resonance spectra of squaric acid has been measured and the electric field gradient tensors at the 17OH--O and 17O---HO sites have been determined from −5 to 144°C. The phase transition is connected with a dynamic order-disorder transition of the protons moving between two potential minima in the H bonds. Local in-plane short-range order along the OH--O-bonded chains was found to persist far above Tc. From the proton-17O magnetic dipolar coupling an 17OH--O length of 2.47 Å and a distance between the two proton equilibrium sites of 0.41 Å has been deduced.
    Journal of Magnetic Resonance 02/2013; 58(3):359-369. DOI:10.1016/0022-2364(84)90141-0 · 2.32 Impact Factor
  • J. Seliger, V. Žagar, R. Blinc
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    ABSTRACT: The 14N quadrupole coupling constant and asymmetry parameter η have been measured (using a double-resonance technique) as a function of temperature in the smectic A, smectic C, and smectic H phases of achiral TBBA and chiral TBACA, as well as in the smectic VI and the solid phase of TBBA. In the low-temperature smectic H and smectic VI phases of achiral TBBA the results clearly demonstrate the existence of bipolar orientational ordering 〈cos2ϕ〉≠0 whereas they show the existence of polar orientational order 〈cosϕ〉≠0 in the smectic H phase of chiral TBACA. Here 〈cosϕ〉∝(Tc-T)β with β=0.33±0.02. In the smectic C phase of both systems the 14N nuclear-quadrupole-resonance spectrum is mainly determined by anisotropic fluctuations in the long molecular axis and the orientational order parameters can be only roughly estimated.
    Physical Review A 02/2013; 17(3). DOI:10.1103/PhysRevA.17.1149 · 2.99 Impact Factor
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    ABSTRACT: In the presence of external fields or in restricted geometries, the originally continuous helical symmetry of the Sm C* phase is broken by the appearence of field- or geometry-induced soliton-like domain walls. As a result of this symmetry breaking, a crossover between the plane-wave-like and soliton-like regime occurs in both static and dynamic properties which is responsible for some remarkable phenomena such as field-induced optical biaxiality or a field-induced band structure of collective excitations. Whereas we find in the plane-wave-like regime a degenerate soft mode which splits below the Sm A→Sm C* transition into a symmetry recovering Goldstone-phason-mode and an amplitudon mode, we find in the soliton regime a splitting of the phason mode into acoustic and optic-like branches separated by a band gap. Within the same framework we also discuss other remarkable and extraordinary properties such as reentrant phases, Lifshitz points, one dimensional photonic band gaps and thickness dependent phase diagrams.
    International Journal of Modern Physics B 05/2012; 09(18n19). DOI:10.1142/S0217979295000902 · 0.46 Impact Factor
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    ABSTRACT: We combine a wide variety of experimental techniques to analyze two heretofore mysterious phase transitions in multiferroic bismuth ferrite at low temperature. Raman spectroscopy, resonant ultrasound spectroscopy, EPR, X-ray lattice constant measurements, conductivity and dielectric response, specific heat and pyroelectric data have been collected for two different types of samples: single crystals and, in order to maximize surface/volume ratio to enhance surface phase transition effects, BiFeO3 nanotubes were also studied. The transition at T=140.3K is shown to be a surface phase transition, with an associated sharp change in lattice parameter and charge density at the surface. Meanwhile, the 201K anomaly appears to signal the onset of glassy behaviour.
    Physical review. B, Condensed matter 02/2012; 85(18). DOI:10.1103/PhysRevB.85.184104 · 3.66 Impact Factor
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    ABSTRACT: The ESR and NMR lines in powder samples of TDAE-C60 do not show the expected frequency shifts due to long range ordering in the low temperature magnetic phase, but instead show only a relatively small line broadening below Tc=16 K. The temperature dependence of the lineshapes in ESR, the absence of a spontaneous magnetization as well as other magnetic properties suggest that the magnetic ordering below Tc=16 K is local and random, i.e. spin-glass like, rather than ferromagnetic. The possible finite-particle-size effects and possible microscopic mechanisms for the observed magnetic behavior are discussed.
    International Journal of Modern Physics B 01/2012; 06(23n24). DOI:10.1142/S021797929200205X · 0.46 Impact Factor
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    ABSTRACT: The narrow components in the 93Nb(I = 9/2) and 45Sc(I = 7/2) NMR spectra of single crystalline PMN and disordered single crystalline PST are due to the 1/2 → -1/2 NMR transition whereas the broad background components are due to satellite transitions.
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    ABSTRACT: The motionally averaged electric field gradient tensors at the Ti-sites have been evaluated within the 8-site Ti disorder model for the various phases of BaTiO3. The results have been compared with the experimental data and with the observation of a non-zero Ti quadrupole coupling in the cubic phase. The pure 8-site “order-disorder” model does not agree with the experiment. A good agreement is however obtained if in addition to the dynamic Ti disorder the “displacive” soft mode induced deformation of the unit cell shape is taken into account. The presence of the soft mode and the Ti disorder leads to a special type of phase transition with combined “displacive” and “order-disorder” character.
    Integrated Ferroelectrics 10/2011; 2004(Vol. 61):255-260. DOI:10.1080/10584580490460231 · 0.37 Impact Factor
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    J F Scott, R Blinc
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    ABSTRACT: An additional eight or ten fluorides with multiferroic phases are listed as an addendum to our recent review ‘Multiferroic Fluorides’ (Scott J F and Blinc R 2011 J. Phys.: Condens. Matter 23 113202).
    Journal of Physics Condensed Matter 07/2011; 23(29):299401. DOI:10.1088/0953-8984/23/29/299401 · 2.22 Impact Factor
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    ABSTRACT: The dielectric response of Rb0.5(ND4)0.5D2PO4 (DRADP-50) dipolar glass has been studied at low temperatures. From the experimental results, the distribution of the relaxation times and of the local polarization at various temperatures is calculated. It is shown that the local-polarization distribution function obtained from the dielectric response e*(�,T) is consistent with that obtained from NMR results. The results also show that the dielectric dispersion is due to diffusion, creation, and annihilation of Takagi groups.
    Journal of Applied Physics 06/2011; 109(11):114101. DOI:10.1063/1.3590147 · 2.19 Impact Factor
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    ABSTRACT: We predict that undoped nanoparticles (size ≤ 10–100 nm) of incipient ferroelectrics without any magnetic ions can become ferromagnetic even at room temperatures due to the inherent presence of a new type of magnetic defects with spin S = 1, namely oxygen vacancies, where the magnetic triplet state is the ground state in the vicinity of the surface (magnetic shell), while the nonmagnetic singlet is the ground state in the bulk material (nonmagnetic core). In particular, for a particle radii R less than the critical radius R c (T) ferromagnetic long-range order appears in a shell region of thickness 5–50 nm once the concentration of magnetic defects N exceeds the magnetic percolation threshold N<sup>p</sup>. At vacancy concentrations N < N<sup>p</sup> and radii R < R c (T), short-range ferromagnetic order and consequently a spin glass state may appear. For particle radii R > R c (T), only the paramagnetic phase is possible.
    Journal of Applied Physics 06/2011; 109(9-109):094105 - 094105-5. DOI:10.1063/1.3580478 · 2.19 Impact Factor
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    ABSTRACT: Using the symmetry theory we analyze of the flexomagnetic effect in all 90 magnetic classes and showed that 69 of them are flexomagnetic. Then we explore how the symmetry breaking, inevitably present in the vicinity of the surface, changes the local symmetry and thus the form of the flexomagnetic tensors. All possible surface magnetic classes (in the number of 19) were obtained from the 90 bulk magnetic classes for the surface cuts 001, 010 and 100 types. It appeared that all 90 bulk magnetic classes become flexomagnetic, piezomagnetic and piezoelectric in the vicinity of surface. Using the free energy approach, we show that the flexomagnetic effect leads to a new type of flexo-magnetoelectric (FME) coupling in nanosized and bulk materials, in all spatial regions, where the polarization and (anti)magnetization vectors are spatially inhomogeneous due to external or internal forces. The linear FME coupling, proportional to the product of the gradients of (anti)magnetization and polarization, flexoelectric and flexomagnetic tensors, is significant in nanosized ferroelectrics-(anti)ferromagnetics, where gradients of the polarization and magnetization obligatory exist. The spontaneous FME coupling induced by the spatial confinement give rise to the size-dependent linear magnetoelectric coupling in nanosized ferroelectrics-(anti)ferromagnetics. We show that the flexomagnetic effect may lead to improper ferroelectricity in bulk (anti)ferromagnetics via the linear and nonlinear FME coupling. Inhomogeneous spontaneous polarization is induced by the (anti)magnetization gradient, which exists in all spatial regions, where polarization varies and (anti)magnetization vector changes its direction. The gradient can be induced by the surface influence as well as by external strain via e.g. the sample bending.
    Physical review. B, Condensed matter 03/2011; 84. DOI:10.1103/PhysRevB.84.174112 · 3.66 Impact Factor
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    ABSTRACT: We show that geometrical confinement of Sm C* type ferroelectric liquid crystals between two parallel boundaries separated by a distance d induces a soliton structure similar to the one obtained in a transverse external magnetic field. For non-polar surface anchoring (i.e., quadrupolar boundary conditions) the (T, d) phase diagram in fact closely resembles the (T, H) phase diagram and the unwinding of the smectic C* helix is preceded by a transition from the plane-wave to the soliton like helical structure. The periodic potential of the soliton lattice induces a gap in the phason dispersion relation similar to the gaps between the valence and conduction bonds of an electron in a periodic potential. For a system with polar boundary conditions the splay distortion of the director field is accompenied by a splayed polarization and a soliton like deformation of the phase profile across the cell. A transverse solitary wave excitation with a (l/d 2) relaxation rate thickness dependence and a finite frequency gap at l/d 2 = 0 has been observed at small thicknesses. A cross-over to a gapless plane-wave like dynamics has been found at large thicknesses.
    Ferroelectrics 03/2011; 206(1):11-30. DOI:10.1080/00150199808009146 · 0.38 Impact Factor
  • J F Scott, R Blinc
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    ABSTRACT: We review work on multiferroic magnetic fluorides with an aim to correct the popular opinion that magnetic ferroelectrics are rare in nature. After a qualitative summary describing the main families of magnetic fluorides that are piezoelectric and probably ferroelectric, we discuss in detail the most popular recent groups, namely the K(3)Fe(5)F(15) and Pb(5)Cr(3)F(19) families.
    Journal of Physics Condensed Matter 03/2011; 23(11):113202. DOI:10.1088/0953-8984/23/11/113202 · 2.22 Impact Factor
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    ABSTRACT: The temperature dependence of the 13C NMR chemical shifts has been measured in the isotropic, the smectic A and the smectic C* phases of chiral DOBAMBC (p-decyloxybenzylidene p′-amino 2-methyl butyl cinnamate) and HOBACPC (hexyloxybenzylidene p′-amino 2-chloro α propyl cinnamate).
    Ferroelectrics 02/2011; 58(1):115-132. DOI:10.1080/00150198408237863 · 0.38 Impact Factor
  • R. Blinc, B. Žekš
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    ABSTRACT: Recent developments in the theory of phase transitions in KH2PO4-type crystals are reviewed together with some relevant experiments. The nature of the isotope effect in the static and dynamic properties of these systems on replacing hydrogen by deuterium is discussed. Expressions for the static and dynamic properties derived by four-cluster analysis are compared with those found from a mean field treatment of the Ising model.
    Ferroelectrics 02/2011; 72(1):193-227. DOI:10.1080/00150198708017947 · 0.38 Impact Factor
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    ABSTRACT: Carbon-13 NMR spectra have been obtained for chiral p-decyloxybenzilidene p′-amino 2-methyl butyl cinnamate (DOBAMBC) in the isotropic, smectic A, ferroelectric smectic C* and H* phases using proton enhanced nuclear induction spectroscopy. The aromatic 13C chemical shifts in DOBAMBC decrease on going from the smectic A to the smectic C* phase whereas they increase at the nematic-smectic C transition in achiral n-heptyloxyazoxybenzene (HOAB). This difference can be explained by the fact that the long molecular axes are tilted with respect to the magnetic field direction in the chiral smectic C* phase of DOBAMBC, whereas they remain parallel to the field direction in the smectic C phase of achiral HOAB.
    Ferroelectrics 02/2011; 24(1):215-218. DOI:10.1080/00150198008238646 · 0.38 Impact Factor
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    ABSTRACT: Physical upper bounds on the electrocaloric effect �ECE� in bulk polar solids are derived using thermodynamic and statistical mechanics arguments. It is shown that the maximum ECE temperature change �T under saturation can be estimated from the dielectric data, such as the saturation polarization and effective Curie constant, as well as from the orientational degeneracy � of the elementary dipolar entities in the system and the specific heat of the material. Also obtained is a universal relation for the theoretical maximum value of �T, which depends only on � and the molar specific heat.
    Applied Physics Letters 01/2011; 98(2):021909. DOI:10.1063/1.3543628 · 3.52 Impact Factor
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    ABSTRACT: Based on our analytical results [http://arxiv.org/abs/1006.3670], we predict that undoped nanoparticles (size <10-100nm) of incipient ferroelectrics without any magnetic ions can become ferromagnetic even at room temperatures due to the inherent presence of a new type of magnetic defects with spin S=1, namely oxygen vacancies, where the magnetic triplet state is the ground state in the vicinity of the surface (magnetic shell), while the nonmagnetic singlet is the ground state in the bulk material (nonmagnetic core). Consideration of randomly distributed magnetic spins (S=1) had shown that magnetic properties of incipient ferroelectric nanoparticles are strongly size and temperature dependent due to the size and temperature dependence of their dielectric permittivity and the effective Bohr radius proportional to permittivity. The phase diagrams in coordinates temperature - particle radius are considered. In particular, for particle radii less that the critical radius ferromagnetic long-range order appears in a shell region of thickness 5 - 50 nm once the concentration of magnetic defects exceeds the magnetic percolation threshold. The critical radius is calculated in the mean field theory from the condition of the magnetic defects exchange energy equality to thermal energy. For particle radii higher than critical value only the paramagnetic phase is possible. The conditions of the super-paramagnetic state appearance in the assembly of nanoparticles with narrow distribution function of their sizes are discussed also. Comment: 33 pages, 7 figures, 2 appendices

Publication Stats

11k Citations
2,773.12 Total Impact Points

Institutions

  • 1178–2013
    • University of Ljubljana
      • • Department of Physics
      • • Faculty of Mathematics and Physics
      • • Institute of Mathematics, Physics, and Mechanics
      • • Laboratory of Physics
      Lubliano, Ljubljana, Slovenia
  • 1960–2012
    • Jožef Stefan Institute
      • • Department of Condensed Matter Physics
      • • Theoretical Physics
      • • Solid State Physics
      • • Department of Physics
      Lubliano, Ljubljana, Slovenia
  • 1976–2011
    • Eawag: Das Wasserforschungs-Institut des ETH-Bereichs
      Duebendorf, Zurich, Switzerland
  • 1986–2006
    • University of Waterloo
      Waterloo, Ontario, Canada
  • 2004
    • Ioffe Physical Technical Institute
      Sankt-Peterburg, St.-Petersburg, Russia
  • 2000
    • Joint Institute for Nuclear Research
      • Frank Laboratory of Neutron Physics
      Dubno, Moskovskaya, Russia
  • 1998
    • Max Planck Institute for Medical Research
      Heidelburg, Baden-Württemberg, Germany
  • 1995
    • University of Sussex
      • Department of Chemistry
      Brighton, England, United Kingdom
  • 1989–1994
    • University of Vienna
      • Basic Experimental Physics Training and Didactics Group
      Vienna, Vienna, Austria
  • 1992
    • Radboud University Nijmegen
      Nymegen, Gelderland, Netherlands
  • 1968–1986
    • French National Centre for Scientific Research
      Lutetia Parisorum, Île-de-France, France
  • 1985
    • University of Utah
      Salt Lake City, Utah, United States
  • 1979
    • University of Lausanne
      Lausanne, Vaud, Switzerland
  • 1978–1979
    • Federal University of Minas Gerais
      • Departamento de Física
      Belo Horizonte, Estado de Minas Gerais, Brazil
  • 1971–1977
    • Stockholm University
      • Department of Biochemistry and Biophysics
      Tukholma, Stockholm, Sweden
  • 1969–1975
    • ETH Zurich
      • Laboratory for Solid State Physics
      Zürich, ZH, Switzerland
    • Argonne National Laboratory
      Lemont, Illinois, United States
  • 1974
    • Kent State University
      Kent, Ohio, United States
  • 1968–1969
    • University of Washington Seattle
      Seattle, Washington, United States