Eduard Tutis

Institute of Physics, Zagreb

Transition-metal dichalcogenides (TMDs) are layered compounds that support many electronic phases, including various charge density waves, superconducting, and Mott insulating states. Their intercalation with magnetic ions introduces magnetic sublayers, which strongly influence the coupling between host layers, and feature various magnetic states a...

Co1/3NbS2 is the magnetic intercalate of 2H-NbS2 where electronic itinerant and magnetic properties strongly influence each other throughout the phase diagram. Here we report the angle-resolved photoelectron spectroscopy (ARPES) study in Co1/3NbS2. In agreement with previous reports, the observed electronic structure seemingly resembles the one of...

Co$_{1/3}$NbS$_2$ is the magnetic intercalate of 2H-NbS$_2$ where electronic itinerant and magnetic properties strongly influence each other throughout the phase diagram. Here we report the first angle-resolved photoelectron spectroscopy (ARPES) study in Co$_{1/3}$NbS$_2$. The observed electronic structure seemingly resembles the one of the parent...

The scattering of electrons on impurities with internal degrees of freedom is bound to produce the signatures of the scatterer's own dynamics and results in nontrivial electronic transport properties. Previous studies of polaronic impurities in low-dimensional structures, like molecular junctions and one-dimensional nanowire models, have shown that...

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. Here, we show that this rule does not hold for 1T-TaS2—a compound with the richest phase diag...

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. Here, we show that this rule does not hold for 1T-TaS 2-a compound with the richest phase dia...

Co$_{1/3}$NbS$_2$ is the only magnetically intercalated layered transition metal dichalcogenide (TMD) suggested to experience the complete suppression of magnetic order under pressure. From elastic neutron scattering we report the direct evidence for the reduction of the antiferromagnetic ordering temperature under pressure, up to complete suppress...

Layered metallic transition-metal dichalcogenides are conventionally seen as two-dimensional conductors, despite a scarcity of systematic studies of the interlayer charge transport. Motivated by the ascending strategy of functionalizing 2D materials by vertical heterostructures we initiated an in-depth study of out-of-plane charge dynamics and emer...

We show that polaronic impurities, characterized by a significant electron-phonon interaction (EPI), may be a source of resonant electron scattering in bulk systems. Using Green's function formalism, partial cross-sections for elastic and inelastic processes are calculated exactly to all orders in the static and the dynamic interaction between the...

Layered metallic transition-metal dichalcogenides are conventionally seen as two-dimensional conductors, despite a scarcity of systematic studies of the interlayer charge transport conducted in a well-defined geometry. Here, we reveal c-axis-oriented quasi-one-dimensional electronic states in 1T-TaS2, a layered system hosting a plethora of diverse...

Layered metallic transition-metal dichalcogenides are conventionally seen as two-dimensional conductors, despite a scarcity of systematic studies of the interlayer charge transport conducted in a well-defined geometry. Here, we reveal c-axis-oriented quasi-one-dimensional electronic states in 1T-TaS2, a layered system hosting a plethora of diverse...

\alpha$-(BEDT-TTF)$_2$I$_3$ is a prominent example of charge ordering among organic conductors. In this work we explore the details of transport within the charge-ordered as well as semimetallic phase at ambient pressure. In the high-temperature semimetallic phase, the mobilities and concentrations of both electrons and holes conspire in such a way...

The controversy regarding the precise nature of the high-temperature phase of 1T−TiSe2 lasts for decades. It has intensified in recent times when new evidence for the excitonic origin of the low-temperature charge-density wave state started to unveil. Here we address the problem of the high-temperature phase through precise measurements and detaile...

The intrinsic d.c. electrical resistivity ($\rho$) - measurable on single crystals only - is often the quantity first revealing the properties of a given material. In the case of CH$_3$NH$_3$PbI$_3$ perovskite measuring $\rho$ under white light illumination provides insight into the coexistence of extended and shallow localized states (0.1 eV below...

We simulate the process of a dark-injection transient spectroscopy (DITS) measurement on an amorphous organic thin film, by modeling the charge transport on a ‘microscopic’ level, with carriers hopping through a three-dimensional network of energetically disordered sites. Our aim is to see what restrictions have to be placed on the form of the ener...

This is the first study of the effect of pressure on transition metal dichalcogenides (TMDs) intercalated by atoms that order magnetically. Co0.33NbS2 is a layered system where the intercalated Co atoms order antiferromagnetically at TN = 26 K at ambient pressure. We have conducted a detailed study of dc-resistivity (ρ), thermoelectric power (S), a...

Hopping between localized polaronic states, with a Gaussian distribution in energy, is regarded as the main mechanism of electric conduction in disordered organics. Several authors have recently suggested that the hopping electrons, subjected to an electric field, can be described as a homogeneous ‘overheated’ gas, with its “effective temperature”...

Electrical conductivity, σ, and thermoelectric power, S, of the monocrystalline T-Al72.5Mn21.5Fe6 complex metallic alloy have been investigated in the temperature range from 2 to 300 K. The crystallographic-direction-dependent measurements were performed along the [0 0 1], [0 1 0] and [1 0 0] directions of the orthorhombic unit cell, where the stac...

We present a model for organic bistable devices (OBDs) embedded with metallic nanoparticles. The model takes into account charge transport through the organic material, field-dependent charge carrier mobility, and injection from the electrodes. The charge trapped by the nanoparticles induces space charge effects that reduce the electric field at th...

Recent numerical simulations of the electronic hopping conduction in disordered organics have indicated that the effective temperature may be suitable to describe the ensemble of electrons in the electric field. However, the reasons for the emergence of the effective temperature have not been clarified, and only phenomenological expressions for the...

We report the experimental results for the electrical conductivity and the thermoelectric power of the complex intermetallic polygrain compound T-Al 73Mn27. The electrical conductivity shows the nonmetallic behavior, but with finite value in the T = 0 limit, and with unusual √T term appearing at the low temperature. This indicates the existence of...

We report the experimental results for the electrical conductivity and the thermoelectric power of the complex intermetallic polygrain compound T-Al73Mn27 The electrical conductivity shows the nonmetallic behavior, but with finite value in the T = 0 limit, and with unusual root T term appearing at the low temperature. This indicates the existence o...

Recent numerical simulations of the electronic hopping conduction in disordered organics have indicated that the effective temperature may be suitable to describe the ensemble of electrons in the electric field. However, the reasons for the emergence of the effective temperature have not been clarified, and only phenomenological expressions for the...

Electrical conductivity, sigma, and thermoelectric power, S, of the monocrystalline T-Al72.5Mn21.5Fe6 complex metallic alloy have been investigated in the temperature range from 2 to 300 K. The crystallographic-direction-dependent measurements were performed along the [0 0 1], [0 1 0] and [1 0 0] directions of the orthorhombic unit cell, where the...

The interplay between superconductivity and the charge-density wave (CDW) state in pure 1T-TiSe(2) is examined through a high-pressure study extending up to pressures of 10 GPa between sub-Kelvin and room temperatures. At a critical pressure of 2 GPa a superconducting phase sets in and persists up to pressures of 4 GPa. The maximum superconducting...

Measurements of the diffusion length L for triplet excitons in small molecular-weight organic semiconductors are commonly carried out using a technique in which a phosphorescent-doped probe layer is set in the vicinity of a supposed exciton generation zone. However, analyses commonly used to retrieve $L$ ignore microcavity effects that may induce a...

The search for the coexistence between superconductivity and other collective electronic states in many instances promoted the discovery of novel states of matter. The manner in which the different types of electronic order combine remains an ongoing puzzle. 1T-TaS(2) is a layered material, and the only transition-metal dichalcogenide (TMD) known t...

Multilayer organic electroluminescent devices derive their advantages over their single-layer counterparts from the processes occurring at heterojunctions in organic media. These processes significantly differ from those in the bulk of the material. This paper presents three-dimensional modeling, numerical simulations, and a discussion of transport...

A one-dimensional system with anharmonic energy of the Landau type is considered. The motion of the system is governed by Newton's equations. It is shown that unexpectedly a dispersive mode describes the dynamics of this system near the mean-field transition temperature. The universal functions which describe the correlation in time and space are o...

We performed high-pressure transport measurements on high-quality single crystals of KOs2O6, a �-pyrochlore superconductor. While the resistivity at high temperatures might approach saturation, there is no sign of saturation at low temperatures, down to the superconducting phase. The anomalous resistivity is accompanied by a nonmetallic behavior in...

In this lecture we present some interesting issues that arise when the dynamics of the charge carriers in the CuO2 planes of high temperature superconductors is considered. Based on the qualitative picture of doping, set by experiments and some previous calculations, we consider the strength of the various inter- and intra-cell charge transfer susc...

Significant progress is being made in the photovoltaic energy conversion using organic semiconducting materials. One of the focuses of attention is the morphology of the donor−acceptor heterojunction at the nanometer scale, to ensure efficient charge generation and loss-free charge transport at the same time. Here, we present a method for the contr...

The process of hopping transport across organic heterojunctions is critical to the function of organic light-emitting diodes (OLED) and many other currently developed organic electronic devices. We consider the case of a hole-only or homopolar heterojunction with Gaussian energetic disorder. We cross-compare the results of our previous multiparticl...

We develop a new three-dimensional multiparticle Monte Carlo ({\it 3DmpMC}) approach in order to study the hopping charge transport in disordered organic molecular media. The approach is applied here to study the charge transport across an energetically disordered organic molecular heterojunction, known to strongly influence the characteristics of...

By using pyran-containing donor-acceptor dyes as doping molecules in organic light-emitting devices (OLEDs), we scrutinize the effects of charge trapping and polarization induced by the guest molecules in the electro-active host material. Laser dyes 4-(dicyanomethylene)-2-methyl-6-[2-[(julolidin-9-yl)phenyl]ethenyl]-4H-pyran (DCM2) and the novel 4-...

We consider charge injection from a metal into amorphous organic molecular media with correlated disorder. It is shown that correlations, known to be essential for understanding the field dependence of the carrier mobility, also strongly influence the injection current distribution. In particular, we find that the injection hot spots are intrinsic...

The remarkable effect on lifetime improvement of copper phthalocianine (CuPc) coated indium tin oxide (ITO) anode of organic light emitting diodes (OLED's) is experimentally well approved. Also known are the electrode morphology, with and without CuPc coating, the energy levels of the used materials, important for charge injection and conduction, t...

We present a theoretical and experimental study of a multilayer organic light emitting device (OLED) with a partially doped emission layer. An extended version of our established "MOLED" device model is used to understand the effects of the partially doped layer on the transport behavior and on the radiative charge recombination distribution as a f...

In organic light emitting devices, doping of the electroactive organic layer with highly luminescent molecules has been shown to considerably increase device performance and lifetime. In most cases, the doping molecule does not act as a charge donor or an acceptor as in classical semiconductors, but is used to enhance light emission and to tune the...

MOLED solves the dynamics of electrons and holes in multilayer organic light emitting diodes (OLED). The carriers are injected on the positive and negative electrodes of the device by tunneling through a potential barrier. Thermal excitation processes across the barrier are also included. In the interior of the device the electron-hole recombinatio...

The internal electric field in multilayer organic light-emitting diodes (OLEDs) is investigated using a combination of experimental measurement and numerical device modeling. This approach results in a detailed understanding of the functioning of a multilayer OLED. The method is applied to a standard device structure that has received broad attenti...

We present a recently developed numerical code for OLED simulation. This code contains a detailed description of contacts, charge transport and recombination. Its efficiency is briefly shown through examples of single- and bilayer devices and discussed in more detail through the investigation of the action of a LiF thin film on injection. In partic...

We present a recently developed numerical code for OLED simulation. This code contains a detailed description of contacts, charge transport and recombination. The route towards the simulation of a complex multilayer device is detailed through examples of single-layer and bilayer devices simulations as well as through the investigation of the action...

An extensive numerical model recently developed for the multilayer organic light-emitting diode is described and applied to a set of real devices. The model contains a detailed description of electrical contacts including dipolar layer formation, thermionic and tunneling injection, space charge effects, field dependent mobilities and recombination...

The system of conducting electrons which interact through the long-range Coulomb force which in addition are coupled to the 2kF deformed lattice is considered within the generalised Tomonaga model for spinless fermions. The T=0 gap Delta L in the electron spectrum is evaluated using the self-consistent harmonic approximation for the excitation spec...

We have developed an OLED transport and injection numerical code. The model contains a detailed description of contacts including the dipolar layer formation, thermoionic and tunneling injection, as well as the space charge effects, field dependent mobilities and recombination processes. The crossovers between different regimes of the diode operati...

The effect of an image force on the barrier for the injection of the carrier from the electrode into the organic layer is shown to be essential for proper understanding of the metal/organic contact and, in particular, of recent results of internal photoemission experiments for metal/Alq3 interfaces. While the calculation presented does not depend o...

Studies of the effect of uncharged niobium impurities on the transport properties in (TaSe4)2 show that the Peierls transition Tp≈250–260K in the pure specimens is smeared out and suppressed in the alloys. The temperature of the Peierls transition Tp and the low temperature energy gap Δ decrease linearly by increasing impurity concentration. In add...

We report measurements of the thermal conductivity (κ) of pure (TaSe4)2I and niobium doped (Ta0.99Nb0.01Se4)2I, in the temperature range 100–340 K. Results show that the Peierls transition in pure (TaSe4)2I is smeared in doped (Ta0.99Nb0.01Se4)2I sample. The self-consistent analysis of all contributions to the thermal conductivity of pure (TaSe4)2I...

We report measurements of the thermal conductivity (κ) of pure (TaSe4)2I and niobium doped (Ta0.99Nb0.01Se4)2I, in the temperature range 100–340K. Results show that the Peierls transition in pure (TaSe4)2I is smeared in doped (Ta0.99Nb0.01Se4)2I sample. The self-consistent analysis of all contributions to the thermal conductivity of pure (TaSe4)2I...

We present a microscopic theory of charge transport in conjugated polymers based on polaron drift along polymer segment and on polaron hopping between segments. We show that this model is able to reproduce the current-voltage characteristics of 'good' hole-only devices based on PPV in the whole range of fields. We also present a microscopic theory...

A Comment on the Letter by T. Mizokawa and A. Fujimori, Phys. Rev. Lett. 80, 1320 (1998). The authors of the Letter offer a Reply.

The qualitative and quantitative features of the electronic charge distribution in cuprate superconductors are reexamined on the basis of a comprehensive set of nuclear quadrupole resonance and NMR measurements. A systematic analysis of measured electric-field gradients is performed within the tight-binding approach, commonly used for electronic mo...

In this lecture we present some interesting issues that arise when the dynamics of the charge carriers in the CuO$_2$ planes of the high temperature superconductors is considered. Based on the qualitative picture of doping, set by experiments and some previous calculations, we consider the strength of various inter and intra-cell charge transfer su...

It is shown that the 3d{3z^{2-r2}} orbital of the in-plane copper and the 2pz apex oxygen orbital are absent at the Fermi level of La{2-x}SrxCuO4, at variance with proposals giving importance to copper-apex oxygen hybridization. At the in-plane oxygen site a sizable 2pz admixture is found at the Fermi level of YBa2Cu3O7. The additional holes are sh...

The effect of the charge fluctuations on the electronic and Raman spectrum of high temperature superconductors is examined, using the slave boson approach to the large Coulomb repulsion $U_d$ on the copper site. Instead of the saddle point approximation $\srv{b}\ne 0$ for the slave boson, characteristic for various $N\ide\infty$ approaches, we conf...

The effect of the charge fluctuations on the electronic spectrum and the Raman spectrum of high temperature superconductors is examined within the slave boson approach. Instead of using the saddle point approximation for slave bosons, we confine ourselves to the non-crossing approximation (NCA) in summing the diagrams for the Green functions, thus...

Using the slave boson approach to treat the Ud → ∞ limit for the Coulomb repulsion on the copper site in the p-d model we give a short account on various charge fluctuation modes. The effect of the slave boson field adjustment on the strength and the Fermi surface effects for and charge transfer modes is discussed. The implications for the screenin...

It is shown that the strong electron-electron repulsion on copper suppresses the coupling of phonons to the copper-oxygen charge fluctuation for large charge transfer gap, in contrast to the coupling to the intracell oxygen-oxygen charge fluctuation, which remains undiminished. In addition, when the Fermi level approaches the van Hove singularity o...

The 4{ital k}{sub {ital F}} response function is recalculated for the one-dimensional electron system in the presence of the umklapp matrix element {ital g}{sub 3}. It is shown that the 1/{omega}{sub {ital c}}{sup 2{minus}4{gamma}} singularity is replaced by a finite value below the energy gap set by {ital g}{sub 3}.

We present Hall effect measurements in the normal state of the high temperature superconducting ceramics La2−xSrxCuO4 (x = 0, 0.05, 0.08, 0.1, 0.15, 0.2, 0.25 and 0.30). The Hall constant (RH) is positive and it is a decreasing function of x.Every Sr gives ∼ 1 hole to the conduction band. For x = 0 RH has semiconductor-like temperature dependence,...

The recent advent of new flat-panel organic displays follows a long struggle for the extended device lifetime. Many modifications proposed along this way have been based on trial and error experimentation. In this paper, we show that some recent major improvements may have been implicitly related to fighting against the strong current filamentation...

It is shown that the 3d$_{3z^{2-r^{2}}}$ orbital of the in-plane copper and the 2p$_z$ apex oxygen orbital are absent at the Fermi level of La$_{2-x}$Sr$_x$CuO$_4$, at variance with proposals giving importance to copper-apex oxygen hybridization. At the in-plane oxygen site a sizable 2p$_z$ admixture is found at the Fermi level of YBa$_2$Cu$_3$O$_7...