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2012

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Laboratory for the physics of transport properties
Head
Dr. Ana Smontara
Co-workers
Dr. Jovica Ivkov, Dr. Petar Popčević, Kristijan Velebit, B. Sc.
Co-workers from other institutions
Dr. Neven Barišić, CEA Saclay France; Doc. dr. Ţeljko Bihar, Faculty of Textile Technology, Dr. Boran
Leontić, Prof. emeritus, Faculty of Science, University of Zagreb, Dr. Jagoda Lukatela, retired.
MAJOR RESULTS
GENERAL OVERVIEW
Activities were focused on the layered systems (transition-metal dichalcogenides and high-Tc superconducting
cuprates), soft feromagnets and metallic glasses. The investigations included measurements of the thermal and
electrical conductivity, thermopower and Hall coefficient under high pressure and magnetic field. The work on
the UKF project contributed to the organization of the workshop “Collaborative Workshop on Modulation and
Nanostructuring in Layered Materials” (http://mnl2012.ifs.hr/) and the international conference “Physics of LowDimensional Conductors: Problems and Perspectives” (http://pldc-pp.ifs.hr/).
Layered systems: Transition-metal dichalcogenides
The research was mainly based on two topics: transport properties of Co intercalated 2H-NbS2 and optical
properties of 1T-TaS2. In CoNbS2 spins on intercalated Co ions undergo antiferromagnetic ordering at 26 K.
This transition temperature decreases with increase of the hydrostatic pressure. Previously investigated transport
properties of CoNbS2 under high pressures, measured by Petar Popčević, have been complemented with
measurements of electrical resistivity perpendicular to the conducting NbS2 layers. While in-layer resistivity
increases with the hydrostatic pressure, resistivity perpendicular to the plane decreases, thus leading to a
considerable decrease of anisotropy. The anisotropy of electrical resistivity under pressure complemented with
Real part of optical conductivity of pure 1T-TaS2. Measurements show the existence of a second phonon peak at low
temperature.
theoretical ab-initio calculations by Ivo Batistić revealed some new insights into the nature of interactions which
lay behind the suppression of the magnetic ordering with pressure.
1T-TaS2 has a rich phase diagram with several charge density wave (CDW) phases. At low temperature the pure
samples are in the insulating commensurate CDW phase with clusters of 13 Ta atoms. At such temperatures the
samples are Mott insulators. At room temperature the samples are in a nearly commensurate CDW phase, where
insulated islands of commensurate charge density wave appear to be separated by incommensurate space
(„mixed phase“). Both, the resistivity and optical conductivity curves measured by Kristijan Velebit show a wide
hysteresis, visible when comparing the measurements taken on cooling and heating. Of significant interest to this
research was the mixed phase of 1T-TaS2. The doping suppresses the Mott transition, so we can investigate its
properties at low temperatures. In collaboration with Eduard Tutiš, a detailed analysis within the Drude-Lorentz
model has reproduced the optical conductivity and phonon frequencies of the samples, as well as some
unexpected features. The analysis shows that that the mixed phase has signature spectra of metal-insulator
composites and has to be analyzed as such. An analysis within the homogeneous model would falsely indentify
the wide features belonging to the surface plasmon resonance as a particularly strong and wide phonon which
could not be accounted for.
Layered systems: High-Tc superconductors
The high-Tc superconducting cuprates on the Mott-insulating side of "optimal doping" exhibit an enigmatic
behavior in the non-superconducting state. Near optimal doping the transport and spectroscopic properties are
unlike those of a Landau-Fermi liquid. For carrier concentrations below optimal doping a pseudogap removes
quasi-particle spectral weight from parts of the Fermi surface, and causes a breakup of the Fermi surface into
disconnected nodal and anti-nodal sectors. Neven Barišić, with co-workers, has shown that the near-nodal
excitations of underdoped cuprates obey the Fermi-liquid behavior. The optical measurements reveal that the
dynamical relaxation rate collapses. The hints of possible Fermi-liquid behavior come from the recently
Dc resistivity of underdoped Hg1201 (Tc = 67 K). Inverse optical conductivity extrapolated to zero frequency (green circles)
compared with measured dc resistivity (1) (solid red line) of a sample of the same composition and doping (A). The dashed
black curve is a T-linear fit to the resistivity data above 350 K. (B) Same dc resistivity data as a function of T2, shown with a
T2 fit to the data below 220 K.
discovered quantum oscillations at low temperature and a high magnetic field in underdoped YBa2Cu3O6+d and
YBa2Cu4O8, from the observed T- square dependence of the DC resistivity for both overdoped and underdoped
cuprates, and from the two-fluid analysis of nuclear magnetic resonance data. However, the direct spectroscopic
determination of the energy dependence of the excitations life-time has been elusive up to now. The observation
defies the standard lore of non-Fermi liquid physics in high-Tc cuprates on the underdoped side of the phase
diagram.
Soft ferromagnets
The ferromagnetic transition-metal and group IV semiconductor alloys such as CoSi and Fe5Si3 attract particular
interest, as they are compatible with existing complementary metal-oxide-semiconductor (CMOS) technologies
and thus can be integrated into future spintronic devices. Moreover, these systems might exhibit a different
symmetry, resulting in very rich phase diagrams. The cubic B20 structure is known to host an elusive spin
texture called Skyrmion while with B82 structure they are ferromagnets even at room temperature. Iron-
germanium phase diagram has attracted much attention due to the sensitivity of iron germanides’s magnetic
properties to the small variation of the composition ratio of Fe and Ge. Petar Popčević, in collaboration with
Jačim Jačimović, has investigated transport and magnetic properties of Fe1.33Ge. At room temperature, the
electrical resistivity is as high as 200 µΩcm and decreases only 4% down to low temperatures which indicates
that this system is very close to Mooji critical behavior. Furthermore, it exhibits a minimum at 20 K
accompanied with a nearly logarithmic low-temperature rise which is usually associated with Kondo effect in
magnetically non-ordered materials. The system is ferromegnetically ordered at room temperature with a
transition temperature higher than 400 K and behaves as a soft ferromagnet. The Hall effect is dominated with a
large anomalous Hall coefficient.
Metallic glasses
In collaboration with Emil Babić and Ramir Ristić, Jovica Ivkov continued to search for the features of
electrical transport properties that would reveal the compositions suitable for the formation of bulk metallic
glasses (BMG). The electrical resistivity and Hall effect, from 90 to 350 K, of Cu xHf100-x metallic glasses with
30≤x≤90 has been investigated. These glasses, together with CuxTi100-x glasses, make a basis, for x = 55, for the
formation of Cu55Hf45-yTiy BMG (which were investigated previous year). It was established that, for both binary
systems, this Cu concentration is equal to that for which there is a sharp change of slope (a knee) in RH vs x
curve, and this curve is sensitive to the effects of electron s-d hybridisation.
PROJECTS
Title: Transport of charge and heat in strongly frustrated magnets and similar materials
Project type: MZOŠ (035-0352826-2848)
Head researcher(s): A. Smontara (IF)
Duration: 01.01. 2007-present
Title: New electronic states driven by frustration in layered materials
Project type: UKF project 1B “Cooperability” Grant-65/10
Head researcher(s): E. Tutiš (IF); L. Forró (EPFL, Lausanne); N. Barišić (CEA Saclay, France); A. Smontara
(IP)
Duration: 15.06. 2010-15. 06. 2012
Title: Modulation and Nanostructuring in Layered Materials
Project type: International Collaborative Workshops
Head researcher(s): A. Smontara (IF); L. Forró (EPFL, Lausanne)
Duration: 01.10. 2011-1.4. 2012.
PARTICIPATION IN RESEARCH NETWORKS
Title: European Integrated Centre for the Development of Metallic Alloys and Compounds (C-MAC)
Network type: EU Network (successor organization of the European Network of Excellence Complex Metallic
Alloys, NoE CMA
Member Institute of Physics (responsible person: A. Smontara)
Duration: 2009-present
PUBLICATIONS
SCIENTIFIC ARTICLES
S. Jazbec, P. Koţelj, S. Vrtnik, Z. Jagličić, P. Popčević, J. Ivkov, D. Stanić, A. Smontara, M. Feuerbacher, and
J. Dolinšek, Electrical, magnetic and thermal properties of the δ-FeZn10 complex intermetallic phase, Phys.
Rev. B 86, 064205 (2012).
M. Klanjšek, A. Gradišek, A. Kocjan, M. Bobnar, P. Jeglič, M. Wencka, Z. Jagličić, P. Popčević, J. Ivkov, A.
Smontara, P. Gille, M. Armbrüster, G. Yu, and J. Dolinšek, PdGa intermetallic hydrogenation catalyst: An
NMR and physical-property study , J. Phys. Condens. Matter 24, 085703 (2012).
M. Bobnar, P. Jeglič, M. Klanjšek, Z. Jagličić, M. Wencka, P. Popčević, J. Ivkov, D. Stanić, A. Smontara, P.
Gille, and J. Dolinšek, Intrinsic anisotropic magnetic, electrical and thermal transport properties of d-Al-Co-Ni
decagonal quasicrystal, Phys. Rev. B 85, 024205 (2012).
EXPERT ARTICLES
Petar Popčević
Osvrt na Nobelovu nagradu za otkriće kvazikristala, Matematičko-fizički list LXII (2011./2012.) 147-153.
Prozirne solarne ćelije, Matematičko fizički list. LXIII (1/249, 2012./2013.) 63-64.
Ultratanke leće, Matematičko fizički list. LXIII (2/250, 2012./2013.) 141-142
PARTICIPATION IN SCIENTIFIC MEETINGS
Ivkov, Jovica; Velebit, Kristijan; Popčević, Petar; Smontara, Ana; Bilušić, Ante; Berger, H.; Forró, László.
Transport properties of 1T-TaS2 single crystal , Physics of Low-Dimnesional Conductors: Problems and
Perspectives, Zagreb, Institute of physics, 25 -28 March 2012 (poster)
Jovica Ivkov, Električna svojstva nemagnetskih amorfnih slitina prijelaznih metala dobivenih brzim kaljenjem i
magnetronskom kodepozicijom, Conference on the occasion of the birth anniversary of Prof. Emil Babić (23
November 2012, Institute of physics, Zagreb)
Petar Popčević, A. Bilušić, J. Dolinšek and A. Smontara, Thermal transport properties of complex metallic
alloys , C-MAC Days 2012, Krakow, Poland, 10 – 13 December 2012 (invited talk).
Petar Popčević, A. Bilušić, K. Velebit and A. Smontara, Thermal transport properties of decagonal quasicrystals
and their approximants, 2012 MRS Fall Meeting, Boston, SAD, 25 – 30 November 2012 (talk).
Petar Popčević, J. Jaćimović, A. Smontara, H. Berger, I. Batistić, J. Piatek, N. Tsyrulin, L.-P. Regnault, N.
Barišić, L. Forró, Electronic Scattering on Frustrated Magnetic System: From Antiferromagnetism to the Kondo
State in Co1/3NbS2 Under Pressure Electronic States and Physers Induced by Electric or Optical Impacts, Orsay,
France, 10 – 14 September 2012 (poster).
Petar Popčević, Measurements of transport properties under high pressure, International workshop UKF
(65/10) project New electronic states driven by frustration in layered materials, Zagreb, 08 June 2012 (talk).
Petar Popčević, J. Jaćimović, I. Smiljanić, A. Bilušić, A. Smontara, H. Berger, Julian Piatek, Nikolay Tsyrulin,
N. Barišić and L. Forró, Magnetic ordering of C0.33NbS2 under pressure, International conference Physics of
low-dimensional conductors: Problems and perspectives, Zagreb 25 -28 Marc 2012 (poster).
Petar Popčević; Transport and ordering in Co0.33NbS2 under pressure up to 1.5 GPa, International workshop
UKF (65/10) project New electronic states driven by frustration in layered materials-Ongoing activities,
Zagreb, 16 January 2012 (talk)
Ana Smontara Physical properties of δ-FeZn10 complex intermetallic, C-MAC Days 2012, Krakow, 10 - 12
December 2012 (talk)
Kristijan Velebit; Popčević, Petar; Smontara, Ana; Berger, H.; Forró, L.; Dressel, M.; Barišić, Neven, The
nano-texture phase of 1T-TaS2 probed by optical conductivtiy, Electronic States and Physes Induced by
Electric or Optical Impacts, Orsay, France, 10 – 14 September 2012 (talk).
Kristijan Velebit, Charge and heat transport in magnetic field, New methods developed within UKF project
65/10, Institute of physics , Zagreb, 08 June 2012 (talk)
Kristijan Velebit; Popčević, Petar; Tutiš, Eduard; Smontara, Ana; Berger, H.; Forró, L.; Eichler, M.; Wu, D.;
Barišić, Neven; Dressel, M., Optical conductivity of the nano-textured phase in 1T-TaS2, "Physics of LowDimensional Conductors: Problems and Perspectives", Program and Abstracts, Institute of physics, Zagreb, 25
-28 March 2012 (poster).
Kristijan Velebit: Recent optical studies in several 1T transition metal dichalcogenides, , International
workshop UKF (65/10) project New electronic states driven by frustration in layered materials-Ongoing
activities, Zagreb, 16 January 2012 (talk)
MENTORSHIP
Ana Smontara
 Kristijan Velebit, doctoral study in physics, Department of Physics, Faculty of Science, University of
Zagreb

Petar Popčević, post-doc at Institute of Physics
SCIENTIFIC VISITS (shorter than 3 months)
Neven Barišić
 Service de Physique de l’Etat Condensé, CEA Sacaly , Paris, France
(25-31 March and 11 -16 October 2012)
Ante Bilušić
 Faculty of Science, University Split, Split, Croatia
(24-31 March , 16-17 May, 12-13 July and 20-21 September 2013)
László Forró
 Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
(14-17 January, 25 -29 March and 05-09 December 2012)
Petar Popčević
 Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
(05/02/-18/02/2012.)
Ana Smontara
 Institute “Joţef Stefan”, Ljubljana, Slovenia
(a few short visit during the year 2012)
Denis Stanić
 Department of Physics, University J. J. Strossmayer Osijek, Osijek, Croatia
(28 -31 March and 17 May 2012)
AWARDS
Kristijan Velebit

Junior Travel Awards Institute for Complex Adaptive Matter (ICAM/I2CAM) to participate on the
international conference, Electronic States and Phases Induced by Electric or Optical Impacts
(IMPACT 2012.), Orsay, 10-14 September 2012
Petar Popčević

Junior Travel Awards Institute for Complex Adaptive Matter (ICAM/I2CAM) to participate on the
international conference, Electronic States and Phases Induced by Electric or Optical Impacts
(IMPACT 2012), Orsay, 10-14 September 2012

CLAD certifikat (Certified LabVIEW Associate Developer).
ORGANIZATION OF SCIENTIFICMEETINGS AND BOARDMEMBERSHIPS
Jovica Ivkov

Member of Local organizing committee International conference Physics of low-dimensional
conductors: Problems and perspectives (25-28 March 2012. Institute of physics, Zagreb)

Member of Local organizing committee Collaborative workshop on Modulation and Nanostructuring in
Layered Materials (28 31 March 2012, Institute of physics, Zagreb)

Member of Organizing committee Conference on the occasion of the birth anniversary of Prof. Emil
Babić (23 November 2012, Institute of physics, Zagreb)
Petar Popčević

Member of Local organizing committee International conference Physics of low-dimensional
conductors: Problems and perspectives (25-28 March 2012, Institute of physics, Zagreb)

Member of Local organizing committee Collaborative workshop on Modulation and Nanostructuring in
Layered Materials (28 31 March 2012, Institute of physics, Zagreb)
Ana Smontara

Organizer of International conference Physics of low-dimensional conductors: Problems and
perspectives (25-28 March 2012, Institute of physics, Zagreb)

Organizer of Collaborative workshop on Modulation and Nanostructuring in Layered Materials (28 31
March 2012, Institute of physics, Zagreb)

Member of the Governing and Science Board European integrated centre for the development of
Metallic Alloys and Compounds (C-MAC)
Kristijan Velebit

Member of Local organizing committee International conference Physics of low-dimensional
conductors: Problems and perspectives (25-28 March 2012, Institute of physics, Zagreb)

Member of Local organizing committee Collaborative workshop on Modulation and Nanostructuring
in Layered Materials (28 - 31 March 2012, Institute of physics, Zagreb)
POPULARIZATION OF PHYSICS
Kristijan Velebit

Presentation of the laboratory high school students of secondary school "Tin Ujević" from Kutina
Institute of physics, Zagreb, 14th May 2012

Presentation of the laboratory high school students of gymnasium “Fran Galović” from Koprivnica,
Institute of physics, 30th May 2012
MISCELLANEOUS
Jovica Ivkov
 Member of the European integrated centre for the development of Metallic Alloys and Compounds (CMAC)
Petar Popčević
 Member of the European integrated centre for the development of Metallic Alloys and Compounds (CMAC)
 Member of the Scientific Council of the Institute of Physics (IP) as one of the representatives of
research assistants
 Member of the Editorail board of the Matematičko-fizički list (MFL) (in Croatian)
Ana Smontara
 Member of the European integrated centre for the development of Metallic Alloys and Compounds (CMAC)

Member of the Editorail board of the Matematičko-fizički list (MFL) (in Croatian)
Kristijan Velebit

Member of the European integrated centre for the development of Metallic Alloys and Compounds (CMAC)
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