Publications by Ana Akrap | EPFL Graph Search

Related publications (37)

Competing orders in strongly correlated systems studied by transport measurements

Competing orders in strongly correlated systems lead to rich phase diagrams comprising many electronic phases, such as superconductivity, charge/spin density wave, charge order, or bad metallicity. These phases are generically sensitive to a variety of par ...

EPFL2008

Optical conductivity of the type-II Weyl semimetal TaIrTe4

Ana Akrap, Konstantin Semeniuk

TaIrTe4 is an example of a candidate Weyl type-II semimetal with a minimal possible number of Weyl nodes. Four nodes are reported to exist in a single plane in k space. The existence of a conical dispersion linked toWeyl nodes has yet to be shown experimen ...

AMER PHYSICAL SOC2020

Optical properties of BiTeBr and BiTeCl

Helmuth Berger, Arnaud Magrez, Philippe Bugnon, Ana Akrap

We present a comparative study of the optical properties-reflectance, transmission, and optical conductivity- and Raman spectra of two layered bismuth-tellurohalides BiTeBr and BiTeCl at 300 and 5 K, for light polarized in the a-b planes. Despite different ...

Amer Physical Soc2014

Transport and magnetic properties of BaVSe3

Helmuth Berger, László Forró, Ana Akrap, Neven Barisic

We report a comprehensive study of transport, magnetotransport, and magnetic properties of single crystals of BaVSe3. The paramagnetic metal-ferromagnetic metal transition at 43 K was followed as a function of pressure by measuring the electrical resistivi ...

2008

Manifestation of the spin textures in the thermopower of MnSi

László Forró, Ana Akrap, Stevan Arsenijevic

To identify possible spin texture contributions to thermoelectric transport, we present a detailed temperature and pressure dependence of thermopower S in MnSi, as well as a lowtemperature study of S in a magnetic field. We find that S/T reconstructs the ( ...

IOP Publishing - EPL Association2013

Synthesis of murunskite single crystals: A bridge between cuprates and pnictides

László Forró, Henrik Moodysson Rønnow, Ivica Zivkovic, Ana Akrap, Edoardo Martino, Davor Tolj, Trpimir Ivsic, Konstantin Semeniuk

Numerous contemporary investigations in condensed matter physics are devoted to high temperature (high-T-c) cuprate superconductors. Despite its unique effulgence among research subjects, the enigma of the high-T-c mechanism still persists. One way to adva ...

ELSEVIER2021

Mahan excitons in room-temperature methylammonium lead bromide perovskites

Majed Chergui, László Forró, Endre Horvath, Ana Akrap, Edoardo Baldini, Márton Kollár, Tania Palmieri

In a seminal paper, Mahan predicted that excitonic bound states can still exist in a semiconductor at electron-hole densities above the insulator-to-metal Mott transition. However, no clear evidence for this exotic quasiparticle, dubbed Mahan exciton, exis ...

Nature Publishing Group2020

Infrared- and Raman-Spectroscopy Measurements of a Transition in the Crystal Structure and a Closing of the Energy Gap of BiTeI under Pressure

Oleg Yazyev, Ana Akrap, Gabriel Albert Autes

BiTeI is a giant Rashba spin splitting system, in which a noncentrosymmetric topological phase has recently been suggested to appear under high pressure. We investigated the optical properties of this compound, reflectivity and transmission, under pressure ...

American Physical Society2014

Probing intraband excitations in ZrTe5: A high-pressure infrared and transport study

Helmuth Berger, Ana Akrap, Philip Johannes Walter Moll, Matthias Carsten Putzke, Edoardo Martino, Mathieu François Padlewski

Zirconium pentatetelluride, ZrTe5, shows remarkable sensitivity to hydrostatic pressure. In this work we address the high-pressure transport and optical properties of this compound, on samples grown by flux and chemical vapor transport. The high-pressure r ...

2020

Preferential out-of-plane conduction and quasi-one-dimensional electronic states in layered 1T-TaS2

Helmuth Berger, László Forró, Alla Arakcheeva, Ana Akrap, Philip Johannes Walter Moll, Matthias Carsten Putzke, Edoardo Martino, Andrea Pisoni, Luka Ciric, Konstantin Semeniuk

Layered transition metal dichalcogenides (TMDs) are commonly classified as quasi-two-dimensional materials, meaning that their electronic structure closely resembles that of an individual layer, which results in resistivity anisotropies reaching thousands. ...

2020

Magnetic anisotropy of paramagnetic and ferromagnetically ordered state of single crystal BaVSe3

Helmuth Berger, László Forró, Ana Akrap

Anisotropic magnetism of single crystal BaVSe3 was Studied for the first time by the combination of the susceptibility and torque methods. As reported previously for polycrystalline sample, BaVSe3 undergoes ferromagnetic ordering below 43 K. Well above fer ...

2008

Characterization of two electronic subsystems in cuprates through optical conductivity

Ana Akrap, Edoardo Martino, Neven Barisic

Understanding the physical properties of unconventional superconductors as well as of other correlated materials presents a formidable challenge. Their unusual evolution with doping, frequency, and temperature has frequently led to non-Fermi-liquid (non-FL ...

2023

Two-Dimensional Conical Dispersion in ZrTe5 Evidenced by Optical Spectroscopy

Helmuth Berger, Ana Akrap, Edoardo Martino

Zirconium pentatelluride was recently reported to be a 3D Dirac semimetal, with a single conical band, located at the center of the Brillouin zone. The cone's lack of protection by the lattice symmetry immediately sparked vast discussions about the size an ...

AMER PHYSICAL SOC2019

Nature of native atomic defects in ZrTe5 and their impact on the low-energy electronic structure

Helmuth Berger, Oleg Yazyev, Ana Akrap, Shengnan Zhang

Over the past decades, investigations of the anomalous low-energy electronic properties of ZrTe5 have reached a wide array of conclusions. An open question is the growth method's impact on the stoichiometry of ZrTe5 samples, especially given the very small ...

AMER PHYSICAL SOC2020

Structural Phase Transition and Bandgap Control through Mechanical Deformation in Layered Semiconductors 1T-ZrX2 (X = S, Se)

Helmuth Berger, Oleg Yazyev, Ana Akrap, Edoardo Martino, Michele Pizzochero, Kristians Cernevics, Konstantin Semeniuk

Applying elastic deformation can tune a material's physical properties locally and reversibly. Spatially modulated lattice deformation can create a bandgap gradient, favoring photogenerated charge separation and collection in optoelectronic devices. These ...

AMER CHEMICAL SOC2020

Persistent antiferromagnetic order in heavily overdoped Ca1-xLaxFeAs2

László Forró, Henrik Moodysson Rønnow, Ivica Zivkovic, Philip Johannes Walter Moll, Ana Akrap, Edoardo Martino, Sergiy Katrych, Lidia Rocoffort de Vinnière

In the Ca1-xLaxFeAs2 (1 1 2) family of pnictide superconductors, we have investigated a highly overdoped composition (x = 0.56), prepared by a high-pressure, high-temperature synthesis. Magnetic measurements show an antiferromagnetic transition at T-N = 12 ...

2019

BiTeCl and BiTeBr: A comparative high-pressure optical study

Helmuth Berger, Arnaud Magrez, Oleg Yazyev, Philippe Bugnon, Ana Akrap, Gabriel Albert Autes

We here report a detailed high-pressure infrared transmission study of BiTeCl and BiTeBr. We follow the evolution of two band transitions: the optical excitation beta between two Rashba-split conduction bands, and the absorption. across the band gap. In th ...

Amer Physical Soc2017

Charge ordering in substituted and non-stoichiometric BaVS3

Helmuth Berger, László Forró, Ana Akrap

Among the correlated electronic systems, BaVS3 which exhibits both itinerant and localized states as well as a subtle interplay betwen charge, orbital, spin and lattice degrees of freedom, is a model system. Its electronic structure consists in a broad qua ...

2010

Crystal Structure, Transport, and Magnetic Properties of an Ir6+ Compound Ba8Al2IrO14

László Forró, Henrik Moodysson Rønnow, Arnaud Magrez, Alla Arakcheeva, Krunoslav Prsa, Andrea Pisoni, Ana Akrap, Jacim Jacimovic, Sergiy Katrych, Lin Yang, Bastien Dalla Piazza

The novel iridate Ba8Al2IrO14 was prepared as single crystals by self-flux method, thereby providing a rare example of an all-Ir(VI) compound that can be synthesized under ambient pressure conditions. The preparation of all-Ir6+ iridate without using tradi ...

2015

Collective charge excitations below the metal-to-insulator transition in BaVS3

Helmuth Berger, László Forró, Ana Akrap

The charge response in barium vanadium sulfide (BaVS3) single crystals is characterized by dc resistivity and low-frequency dielectric spectroscopy. A broad relaxation mode in the megahertz range with a huge dielectric constant of approximate to 10(6) emer ...

2008