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Item Adaptive Anderson mixing for electronic structure calculations(Elsevier, 2023) Novák, Matyáš; Vackář, Jiří; Cimrman, Robert; Šipr, Ondřej
Item Investigation of carrier transport in ZnO and ZnO:Al thin films sputtered at different oxygen conditions(Elsevier, 2023) Novák, Petr; Nedvědová, Lucie; Kozák, Tomáš; Šotová, Petra; Bláhová, Olga; Jansa, Zdeněk; Medlín, Rostislav; Netrvalová, Marie; Minár, JanItem Effect of Double-Step and Strain-Assisted Tempering on Properties of Medium-Carbon Steel(MDPI, 2023) Salvetr, Pavel; Školáková, Andrea; Kotous, Jakub; Drahokoupil, Jan; Melzer, Daniel; Jansa, Zdeněk; Donik, Črtomir; Gokhman, Aleksandr; Nový, Zbyšek
Item Dynamics of lattice disorder in perovskite materials, polarization nanoclusters and ferroelectric domain wall structures(Nature Research, 2023) Očenášek, Jan; Minár, Jan; Alcalá, JorgeSpojitost mezi klasickou feroelektricitou a strukturou perovskitových materiálů se odvíjí od konceptu mřížkové neuspořádanosti. Ačkoli uspořádané perovskity vykazují krátkodobé posuny centrálních kationtů kolem jejich rovnovážných bodů, mřížková neuspořádanost se dynamicky vyvíjí a vytváří nesčetné množství deformovaných kosočtverečných mřížek charakterizovaných přeskakováním centrálních kationtů ve směrech <111>. Zjistilo se, že mřížková neuspořádanost koreluje se vznikem minimálních konfiguračních energií <100> drah centrálních kationtů, což vede k prostorově modulovaným ultrarychlým polarizačním uspořádáním nanoklastrů, které jsou stabilizovány elektrickými nábojovými defekty v materiálu. Prostřednictvím analýz rozptylu fononů s vysokým rozlišením zahrnujících simulace molekulární dynamiky (MD) a teorie funkcionálu hustoty (DFT) poskytujeme jednoznačné důkazy spojující přeskakování centrálních kationtů s rozvojem difúzních měkkých fononových módů pozorovaných v průběhu fázových přechodů perovskitu. Prostřednictvím rozsáhlých MD simulací odhalujeme vliv mřížkové neuspořádanosti na struktury doménových stěn při konečné teplotě ve vztahu ke kolektivní aktivaci a deaktivaci <100> drah. Naše simulace dále ukazují vývoj hierarchických nanostruktur s morfotropní fázovou hranicí (MPB) pod kombinovaným vlivem externě aplikovaného tlaku a relaxace napětí, charakterizovaných náhlým vznikem klikatých monoklinických uspořádání, která zahrnují dvojí <111> posun centrálních kationtů. Tato zjištění mají význam pro přizpůsobení MPB v tenkovrstvých strukturách a pro světlem indukovanou mobilizaci DW. Závěrem jsou naznačeny cesty ke zkoumání mřížkové neuspořádanosti prostřednictvím postupné aplikace smykové deformace.Item Electronic structure of Bi nanolines on InAs(100)(Elsevier, 2023) Nafday, Dhani; Richter, Christine; Heckmann, Olivier; Wang, Weimin; Mariot, Jean-Michel; Djukic, Uros; Vobornik, Ivana; Lefevre, Patrick; Taleb-Ibrahimi, Amina; Bertran, Franco̧is; Rault, Julien; Nicolai, Laurent Christophe; Ong, Chin Shen; Thunström, Patrik; Hricovini, Karol; Minár, Jan; Di Marco, IgorItem Temperature-induced changes in the magnetism of Laves phase rare-earth-iron intermetallics by ab initio calculations(American Physical Society, 2022) Šipr, Ondřej; Mankovsky, Sergiy; Vackář, Jiří; Ebert, Hubert; Marmodoro, AlbertoItem Single-crystal studies and electronic structure investigation of the room-temperature semiconductor NaMnAs(American Physical Society, 2022) Volný, Jiří; Charvátová, Kateřina; Veis, Martin; Holý, Václav; Vondráček, Martin; Honolka, Jan; Duverger-Nédellec, Elen; Schusser, Jakub; Dsouza, Sunil Wilfred; Minár, Jan; Pientka, James M.; Marmodoro, Alberto; Výborný, Karel; Uhlířová, KláraItem Dependence of the Electronic Structure of β-Si6 - zAlzOzN8 - z on the (Al,O) Concentration z and on the Temperature(Wiley, 2022) Khan, Saleem Ayaz; Šipr, Ondřej; Vackář, Jiří; Minár, JanItem Photoemission signature of momentum-dependent hybridization in CeCoIn5(American Physical Society, 2021) Kurleto, R.; Fidrysiak, M.; Nicolai, Laurent Christophe; Minár, Jan; Rosmus, M.; Walczak, Ł.; Tejeda, A.; Rault, J.E.; Bertran, F.; Kądzielawa, A.P.; Legut, D.; Gnida, D.; Kaczorowski, D.; Kissner, K.; Reinert, F.; Spałek, J.; Starowicz, P.Item Nickel-adsorbed two-dimensional Nb2C MXene for enhanced energy storage applications(Royal Society of Chemistry, 2022) Zaheer, Ayesha; Zahra, Syedah Afsheen; Iqbal, Muhammad Z.; Mahmood, Asif; Khan, Saleem Ayaz; Rizwan, SyedOwing to the tremendous energy storage capacity of two-dimensional transition metal carbides (MXenes), they have been efficiently utilized as a promising candidate in the field of super-capacitors. The energy storage capacity of MXenes can be further enhanced using metal dopants. Herein, we have reported the synthesis of pristine and nickel doped niobium-carbide (Nb2C) MXenes, their computational and electrochemical properties. Upon introduction of nickel (Ni) the TDOS increases and a continuous DOS pattern is observed which indicates coupling between Ni and pristine MXene. The alterations in the DOS, predominantly in the nearby region of the Fermi level are profitable for our electrochemical applications. Additionally, the Ni-doped sample shows a significant capacitive performance of 666.67 F g-1 which can be attributed to the additional active sites generated by doping with Ni. It is worth noting that doped MXenes exhibited a capacitance retention of 81% up to 10 000 cycles. The current study unveils the opportunities of using MXenes with different metal dopants and hypothesize on their performance for energy storage devicesItem Field-induced ultrafast modulation of Rashba coupling at room temperature in ferroelectric alpha-GeTe(111)(Nature Research, 2022) Kremer, Geoffroy; Maklar, Julian; Nicolai, Laurent Christophe; Nicholson, Christopher W.; Yue, Changming; Silva, Caio; Werner, Philipp; Dil, J. Hugo; Krempaský, Juraj; Springholz, Gunther; Ernstorfer, Ralph; Minár, Jan; Rettig, Laurenz; Monney, ClaudeRashba materials have appeared as an ideal playground for spin-to-charge conversion in prototype spintronics devices. Among them, α-GeTe(111) is a non-centrosymmetric ferroelectric semiconductor for which a strong spin-orbit interaction gives rise to giant Rashba coupling. Its room temperature ferroelectricity was recently demonstrated as a route towards a new type of highly energy-efficient non-volatile memory device based on switchable polarization. Currently based on the application of an electric field, the writing and reading processes could be outperformed by the use of femtosecond light pulses requiring exploration of the possible control of ferroelectricity on this timescale. Here, we probe the room temperature transient dynamics of the electronic band structure of α-GeTe(111) using time and angle-resolved photoemission spectroscopy. Our experiments reveal an ultrafast modulation of the Rashba coupling mediated on the fs timescale by a surface photovoltage, namely an increase corresponding to a 13% enhancement of the lattice distortion. This opens the route for the control of the ferroelectric polarization in α-GeTe(111) and ferroelectric semiconducting materials in quantum heterostructures.Item Control of ultrafast laser ablation efficiency by stress confinement due to strong electron localization in high-entropy alloys(Elsevier, 2022) Redka, David; Winter, Jan; Gadelmeier, Christian; Djuranovic, Alexander; Glatzel, Uwe; Minár, Jan; Huber, Heinz PaulIn the context of current state of the art, understanding the laser ablation efficiency decrease for pulse durations High-entropy alloy; CrMnFeCoNi; Ultrafast laser ablation; Pulse duration; Ablation efficiency; Stress confinementexceeding the mechanical relaxation time of a few ps remains a pending research question. A heuristic approach may be used to reveal the role of effective penetration depth on ablation efficiency. Extending familiar contributions of this quantity by a term related to the mechanical surface expansion during pulse irradiation, the relation of ablation efficiency and pulse duration is deciphered. Thus, longer pulses are coupled into an expanded surface, revealing a direct link to the violation of stress confinement. To best demonstrate this hypothesis, a material with high electron–phonon coupling as well as low thermal conductivity, i.e., strong electron localization, is required. These properties are accomplished by high-entropy alloys, and the CrMnFeCoNi alloy serves as prime candidate. We report on single-pulse ablation efficiency experiments of the CrMnFeCoNi alloy which are support by our proposed model.Item Effects of alloying chalcopyrite CuTlSe2 with Na on the electronic structure and thermoelectric coefficients: DFT investigation(Springer, 2022) Djelid, K.; Seddik, T.; Merabiha, O.; Batouche, M.; Khenata, R.; Bouhemadou, A.; Khan, Saleem Ayaz; Bin Omran, S.the chalcopyrite alloys Cu1–xNaxTlSe2, with x = 0.00, 0.25, and 0.50 were studied through density functional theory calculations. The Wu–Cohen generalized gradient and the Tran–Blaha modified Becke–Johnson approximations have been employed to describe the exchange–correlation potential. Energy band structure analysis reveals that CuTlSe2 is a semi-metal, while Cu0.25Na0.75TlSe2 and Cu0.50Na0.50TlSe2 alloys are semiconductors with gaps of approximately 0.17 eV and 0.35 eV, respectively. The total and partial densities of states were calculated and discussed. Examining the charge density, we point out the formation of the Na–Se ionic bond when Cu is replaced by the Na atom, which is responsible for the metal–semiconductor transition in the Cu1–xNaxTlSe2 alloys. Moreover, variations of the Seebeck coefficient, electrical conductivity, electronic and lattice thermal conductivity, power factor, and figure of merit of the Cu1–xNaxTlSe2 alloys with temperature and chemical potential were explored. The obtained results show that the value of the figure of merit increases when doping CuTlSe2 with sodium to reach 0.46 and 0.87 for p-type Cu0.75Na0.25TlSe2 and n-type Cu0.50Na0.50TlSe2, respectivelyItem Direct imaging of valence orbitals using hard x-ray photoelectron spectroscopy(American Physical Society, 2022) Takegami, Daisuke; Nicolai, Laurent Christophe; Utsumi, Yuki; Meléndez-Sans, Anna; Balatsky, Daria A.; Knight, Cariad-A.; Dalton, Connor; Huang, Shao-Lun; Chen, Chi-Sheng; Zhao, Li; Komarek, Alexander C.; Liao, Yen-Fa; Tsuei, Ku-Ding; Minár, Jan; Tjeng, Liu HaoIt was hypothesized already more than 40 years ago that photoelectron spectroscopy should in principle be able to image atomic orbitals. If this can be made to work for orbitals in crystalline solids, one would have literally a different view on the electronic structure of a wide range of quantum materials. Here, we demonstrate how hard x-ray photoelectron spectroscopy can make direct images of the orbitals making up the band structure of our model system, ReO3. The images are energy specific and enable us to unveil the role of each of those orbitals for the chemical bonding and the Fermi surface topology. The orbital image information is complementary to that from angle-resolved photoemission and thus completes the determination of the electronic structure of materials.Item A novel route of colloidal chemistry: room temperature reactive interactions between titanium monoxide and silicon monoxide sols produced by laser ablation in liquid resulting in the formation of titanium disilicide(Royal Society of Chemistry, 2022) Křenek, Tomáš; Vála, Lukáš; Medlín, Rostislav; Pola, Josef; Jandová, Věra; Vavruňková, Veronika; Mikysek, Petr; Bělský, Petr; Koštejn, MartinIn spite of advanced research on functional colloidal inorganic nanoparticles and their reactivity, room temperature reactive interactions between two different colloids have remained challenging so far. Laser ablation of titanium monoxide and silicon monoxide in ethanol and water allows the generation of TiOderived and SiO-derived colloidal nanoparticles which were characterized for their stability, size distribution and zeta potentials with dynamic light scattering and after evaporation of solvent examined for their morphology, chemical and phase composition by scanning electron microscopy, Raman spectroscopy, high resolution transmission electron microscopy and electron diffraction and small angle X-ray scattering. Aqueous and ethanolic TiO-derived colloids consist of anatase and monoclinic TiO, while ethanolic SiO derived colloids are composed of crystalline and amorphous Si, nanocrystalline Si and SiO2 and aqueous SiO-derived colloids contain, in addition to these phases, a high pressure form of cristobalite. Simple room temperature mixing of ethanolic TiO- and SiO-derived colloids allows the formation of TiSi2, which is a case of so far unreported room temperature reactive interactions between two colloidal species. All colloids absorb solar light and act as photocatalysts for methylene blue degradation. These findings present a challenge for further search for feasible room-temperature reactions between distinct colloidal particles and open the potential for green synthesis of other desirable and hardly achievable phases.Item Electric field control of magnons in magnetic thin films: Ab initio predictions for two-dimensional metallic heterostructures(American Physical Society, 2022) Marmodoro, Alberto; Mankovsky, Sergiy; Ebert, Hubert; Minár, Jan; Šipr, OndřejItem Understanding the Role of Electronic Effects in CO on the Pt-Sn Alloy Surface via Band Structure Measurements(American Chemical Society, 2022) Jung, Jongkeun; Kang, Sungwoo; Nicolai, Laurent Christophe; Hong, Jisook; Minár, Jan; Song, Inkyung; Kyung, Wonshik; Cho, Soohyun; Kim, Beomseo; Denlinger, Jonathan D.; Cadete Santos Aires, Francisco José; Ehret, Eric; Ross, Philip; Shim, Jihoon; Nemšák, Slavomir; Noh, Doyoung; Han, Seungwu; Kim, Changyoung; Mun, Bongjin SimonItem Role of chemical disorder in tuning the Weyl points in vanadium doped Co2 TiSn(American Physical Society, 2021) Chaudhary, Payal; Dubey, Krishna Kant; Shukla, Gaurav K.; Singh, Sanjay; Sadhukhan, Surasree; Kanungo, Sudipta; Jena, Ajit K.; Lee, S.-C.; Bhattacharjee, S.; Minár, Jan; Dsouza, Sunil WilfredItem Surface band characters of the Weyl semimetal candidate material MoTe2 revealed by one-step angle-resolved photoemission theory(American Physical Society, 2021) Ono, Ryota; Marmodoro, Alberto; Schusser, Jakub; Nakata, Yoshitaka; Schwier, Eike F.; Braun, Jürgen; Ebert, Hubert; Minár, Jan; Sakamoto, Kazuyuki; Krüger, PeterItem Experimental and Computational Analysis of MnO2@V2C-MXene for Enhanced Energy Storage(MDPI, 2021) Fatima, Mahjabeen; Zahra, Syedah Afsheen; Khan, Saleem Ayaz; Akinwande, Deji; Minár, Jan; Rizwan, Syed
