Abstract:We investigate signatures of electronic correlations in the narrow-gap semiconductor FeGa 3 by means of electrical resistivity and thermodynamic measurements performed on single crystals of FeGa 3 , Fe 1−x Mn x Ga 3 , and FeGa 3−y Zn y , complemented by a study of the 4d analog material RuGa 3 . We find that the inclusion of sizable amounts of Mn and Zn dopants into FeGa 3 does not induce an insulator-to-metal transition. Our study indicates that both substitution of Zn onto the Ga site and replacement of Fe b… Show more
“…A recent example is the electron doping of the intermetallic FeGa 3 that leads to enhanced thermoelectric figures of merit [2][3][4][5][6][7][8][9][10] and to emergent magnetic behavior accompanied by the possible observation of a Ferromagnetic Quantum Critical Point (FMQCP) [11][12][13][14][15][16][17][18][19][20][21] .…”
Section: Introductionmentioning
confidence: 99%
“…FeGa 3 is a semiconductor with tetragonal structure (space group P 4 2 /mnm) 2 and a narrow band gap of approximately 0.5 eV caused by the hybridization of the 3d Fe and 4p Ga bands [2][3][4]16,24,25 . It is diamagnetic over a broad temperature range and has a small Sommerfeld coefficient (γ =0.03 mJ mol K ) 3,11,16 .…”
Temperature dependent magnetization, muon spin rotation and 57 Fe Mössbauer spectroscopy experiments performed on crystals of intermetallic 0.14, 0.17, 0.22, 0.27, 0.29, 0.32) are reported. Whereas at y = 0.11 even a sensitive magnetic microprobe such as µSR does not detect magnetism, all other samples display weak ferromagnetism with a magnetic moment of up to 0.22 µB per Fe atom. As a function of doping and of temperature a crossover from short range to long range magnetic order is observed, characterized by a broadly distributed spontaneous internal field. However, the y = 0.14 and y = 0.17 remain in the short range ordered state down to the lowest investigated temperature. The transition from short range to long range order appears to be accompanied by a change of the character of the spin fluctuations, which exhibit spin wave excitations signature in the LRO part of the phase diagram. Mössbauer spectroscopy for y = 0.27 and 0.32 indicates that the internal field lies in the plane perpendicular to the crystallographic c axis. The field distribution and its evolution with doping suggest that the details of the Fe magnetic moment formation and the consequent magnetic state are determined not only by the dopant concentration but also by the way the replacement of the Ga atoms surrounding the Fe is accomplished.
“…A recent example is the electron doping of the intermetallic FeGa 3 that leads to enhanced thermoelectric figures of merit [2][3][4][5][6][7][8][9][10] and to emergent magnetic behavior accompanied by the possible observation of a Ferromagnetic Quantum Critical Point (FMQCP) [11][12][13][14][15][16][17][18][19][20][21] .…”
Section: Introductionmentioning
confidence: 99%
“…FeGa 3 is a semiconductor with tetragonal structure (space group P 4 2 /mnm) 2 and a narrow band gap of approximately 0.5 eV caused by the hybridization of the 3d Fe and 4p Ga bands [2][3][4]16,24,25 . It is diamagnetic over a broad temperature range and has a small Sommerfeld coefficient (γ =0.03 mJ mol K ) 3,11,16 .…”
Temperature dependent magnetization, muon spin rotation and 57 Fe Mössbauer spectroscopy experiments performed on crystals of intermetallic 0.14, 0.17, 0.22, 0.27, 0.29, 0.32) are reported. Whereas at y = 0.11 even a sensitive magnetic microprobe such as µSR does not detect magnetism, all other samples display weak ferromagnetism with a magnetic moment of up to 0.22 µB per Fe atom. As a function of doping and of temperature a crossover from short range to long range magnetic order is observed, characterized by a broadly distributed spontaneous internal field. However, the y = 0.14 and y = 0.17 remain in the short range ordered state down to the lowest investigated temperature. The transition from short range to long range order appears to be accompanied by a change of the character of the spin fluctuations, which exhibit spin wave excitations signature in the LRO part of the phase diagram. Mössbauer spectroscopy for y = 0.27 and 0.32 indicates that the internal field lies in the plane perpendicular to the crystallographic c axis. The field distribution and its evolution with doping suggest that the details of the Fe magnetic moment formation and the consequent magnetic state are determined not only by the dopant concentration but also by the way the replacement of the Ga atoms surrounding the Fe is accomplished.
“…Это обстоятельство неиз-бежно приводит к появлению в оптической проводимо-сти слабого отклика, вызванного возбуждением коллек-тивизированных электронов полем световой волны. Па-раметры энергетической щели в FeGa 3 и RuGa 3 (глубина и ширина) существенно зависят от температуры, мето-дов синтеза образцов, наличия дефектов и примеси, от-клонения от стехиометричности [12][13][14][15][16], что приводит к значительным изменениям их электронных и магнитных свойств. По-видимому, проявление слабого оптического поглощения в низкоэнергетическом диапазоне спектра также связано с одним из указанных выше факторов.…”
Section: результаты и обсуждениеunclassified
“…Результаты расчетов электронной структуры использовали при интерпрета-ции магнитных и транспортных свойств FeGa 3 и RuGa 3 . В частности, аномалия зонного спектра, связанная с энергетической щелью на E F , определяет поведение температурных зависимостей удельной теплоемкости, электросопротивления, эффекта Холла, коэффициента Зеебека [4][5][6][12][13][14][15][16]. Подобная щель (≤ 0.8 eV) была за-фиксирована в фотоэмиссионных спектрах FeGa 3 [17,18].…”
Section: Introductionunclassified
“…Подобная щель (≤ 0.8 eV) была за-фиксирована в фотоэмиссионных спектрах FeGa 3 [17,18]. В работах [6,[12][13][14][15][16] показано, что температура и нали-чие примесей различных элементов существенно вли-яют на эволюцию параметров энергетической щели, которая принимает характер псевдощели, что, в свою очередь, вызывает изменения в поведении физических характеристик. Кроме того, на электронные и магнит-ные свойства FeGa 3 и RuGa 3 влияют методы синтеза, степень дефектности и нестехиометричность образцов.…”
Проведены исследования оптических свойств интерметаллических соединений FeGa3 и RuGa3 в интервале длин волн 0.22-14 mum. Спектры межзонного поглощения света интерпретируются на основе сравнительного анализа рассчитанных и экспериментальных дисперсионных зависимостей оптической проводимости. Экспериментальные данные подтверждают существование в плотностях состояний данных материалов энергетических щелей на уровне Ферми шириной ~0.6 eV, что ранее предсказывалось в зонных расчетах. Работа выполнена в рамках государственного задания ФАНО России (тема "Электрон", N 01201463326) при частичной поддержке РФФИ (проект N 17-52-45056). DOI: 10.21883/FTT.2017.11.45065.138
EuIr4In2Ge4 is a new intermetallic semiconductor that adopts a non‐centrosymmetric structure in the tetragonal ${I\bar 42m}$ space group with unit cell parameters a=6.9016(5) Å and c=8.7153(9) Å. The compound features an indirect optical band gap Eg=0.26(2) eV, and electronic‐structure calculations show that the energy gap originates primarily from hybridization of the Ir 5d orbitals, with small contributions from the Ge 4p and In 5p orbitals. The strong spin–orbit coupling arising from the Ir atoms, and the lack of inversion symmetry leads to significant spin splitting, which is described by the Dresselhaus term, at both the conduction‐ and valence‐band edges. The magnetic Eu2+ ions present in the structure, which do not play a role in gap formation, order antiferromagnetically at 2.5 K.
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