Magnetic field modulated microwave spectroscopy across phase transitions and the search for new superconductors

Ramírez, Juan Gabriel; Basaran, Ali C.; Venta, J. de la; Pereiro, J.; Schuller, Iván K.

doi:10.1088/0034-4885/77/9/093902

Cited by 16 publications

(44 citation statements)

References 132 publications

(164 reference statements)

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“…MFMMS is a unique technique that allows detection of minuscule superconducting regions in inhomogenous systems faster and with higher sensitivity than most conventional methods [1,20]. MFMMS is based on a measurement of temperature dependent phase sensitive microwave absorption while the sample is subjected to an AC modulated magnetic field.…”

Section: Magnetic Field Modulated Microwave Spectroscopy (Mfmms)mentioning

confidence: 99%

“…MFMMS is based on a measurement of temperature dependent phase sensitive microwave absorption while the sample is subjected to an AC modulated magnetic field. The AC field modulation together with phase sensitive detection is known to produce a sharp peak-like behavior across the superconducting transition [1,20]. The superconducting onset temperature is correlated with the temperature at which the MFMMS signal falls below the background noise level.…”

Section: Magnetic Field Modulated Microwave Spectroscopy (Mfmms)mentioning

confidence: 99%

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Magnetism and the absence of superconductivity in the praseodymium–silicon system doped with carbon and boron

Venta

Basaran

Grant

et al. 2013

Journal of Magnetism and Magnetic Materials

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Keywords:Rare earth compound Praseodymium silicide Magnetism and superconductivity search for new phase High-pressure high temperature a b s t r a c tWe searched for new structural, magnetic and superconductivity phases in the Pr-Si system using highpressure high-temperature and arc melting syntheses. Both high and low Si concentration areas of the phase diagram were explored. Although a similar approach in the La-Si system produced new stable superconducting phases, in the Pr-Si system we did not find any new superconductors. At low Si concentrations, the arc-melted samples were doped with C or B. It was found that addition of C gave rise to multiple previously unknown ferromagnetic phases. Furthermore, X-ray refinement of the undoped samples confirmed the existence of the so far elusive Pr 3 Si 2 phase.

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Section: Magnetic Field Modulated Microwave Spectroscopy (Mfmms)mentioning

confidence: 99%

Section: Magnetic Field Modulated Microwave Spectroscopy (Mfmms)mentioning

confidence: 99%

Magnetism and the absence of superconductivity in the praseodymium–silicon system doped with carbon and boron

Venta

Basaran

Grant

et al. 2013

Journal of Magnetism and Magnetic Materials

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“…The MFMMS-response depends on the materials under investigation [28]. In particular, in a DC magnetic field, as the temperature is swept through the Tc, the AC magnetic field forces the material periodically in and out of the superconducting state.…”

mentioning

confidence: 99%

“…However, in some rare cases (i.e. Mn doped GaAs), a peak in the MFMMS-response is obtained due to magneto-resistive effects or, due to a magnetic field induced change in the skin depth [28]. To discriminate superconducting materials from these rare cases, complementary criteria are used:…”

mentioning

confidence: 99%

“…Refer to [29] for a short introduction and to [28] for an extensive discussion of the MFMMS technique. overall shape is a flat negative response from room temperature to 145 K followed by a rounded, s-shaped step going down, ending at 60 K. Most important, there is a peak with an onset temperature of 117 K. This peak has the same sign as the peak of a reference superconductor MgB 2 that was added to the samples.…”

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confidence: 99%

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Search for New Superconductors: an Electro-Magnetic Phase Transition in an Iron Meteorite Inclusion at 117 K

Guénon

Ramírez

Basaran

et al. 2016

J Supercond Nov Magn

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The discovery of superconductivity in pnictides and iron chalcogenides inspires the search for new iron based superconducting phases. Iron-rich meteorites present a unique opportunity for this search, because they contain a broad range of compounds produced under extreme growth conditions. We investigated a natural iron sulfide based materials (Troilite) inclusion with its associated minerals in the iron meteorite Tlacotepec.Tlacotepec formed in an asteroidal core under high pressure and at high temperature over millions of years, while insoluble sulfur rich materials segregated into inclusions during cooling along with included minerals. The search for superconductivity in these heterogeneous materials requires a technique capable of detecting minute amounts of a superconducting phase embedded in a non-superconducting matrix. We used Magnetic Field Modulated Microwave Spectroscopy (MFMMS), a very sensitive, selective, and non-destructive technique, to search for superconductivity in heterogeneous systems.Here, we report the observation of an electro-magnetic phase transition at 117 K that causes a MFMMS-response typical of a superconductor. A pronounced and reproducible peak together with isothermal magnetic field sweeps prove the appearance of a new electromagnetic phase below 117 K. This is very similar to the characteristic response due to flux trapping in a granular superconductor with a short coherence length. Although the compound responsible for the peak in the MFMMS-spectra was not identified, it is possibly an iron sulfide based phase, or another material heterogeneously distributed over the inclusion. Main Text:The discovery of iron-based superconductors, a new class of superconducting compounds with an unconventional pairing mechanism, has rekindled the interest in the search for new superconducting materials [1][2][3]. Superconducting iron chalcogenides like undoped β-FeSe [4], Fe(Se 1-x Te x ) [5,6] or S-substituted FeTe [7] are of particular interest.The superconducting transition temperature T c of FeSe can be significantly increased by applying high external pressure [8]. Several attempts were made to increase the transition temperature either by high pressure, high temperature synthesis, or by substituting selenium with sulfur that has a smaller atomic radius [9,10]. However, in this study we search for superconductivity in naturally occurring materials instead of synthesizing new compounds. This approach has two advantages: First, we can investigate materials that have crystallized under very extreme conditions like very long cooling time, high

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Controllable Broadband Absorption in the Mixed Phase of Metamagnets

Pregelj

Zaharko

Zorko

et al. 2015

Adv Funct Materials

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wileyonlinelibrary.comunconventional fractional excitations, [1][2][3][4][5][6] nontrivial scale-invariant quantum excitations at quantum critical points, [7][8][9][10][11][12] and nonresonant absorption in superconductors. [ 13 ] In the context of applications, broadband microwave absorption is highly desirable in microwave fi lters, [ 14 ] signalto-noise enhancers, optical signal processing, [15][16][17] electromagnetic interference shielding, [ 18,19 ] etc. Most of these applications are based on conducting materials, even though normal metals possess relatively narrow absorption ranges (typically 100-1000 MHz). [ 18 ] Hence, composite carbon-based materials, [19][20][21] which extend the absorption range from hundreds of kHz up to hundreds of GHz, [ 18 ] and multilayer magnetic structures that cover the range between several GHz and several THz [22][23][24][25][26] are being developed. However, none of these materials allow for external control of their absorption properties, e.g., by the electric or the magnetic fi eld.A class of materials that could allow for a controllable (ondemand) broadband absorption are metamagnets. These systems are, typically, highly anisotropic and, as a function of the external magnetic fi eld, undergo a fi rst-order phase transition from a state with low magnetization to a state with high magnetization. [ 27 ] Prominent examples are layered metamagnets with perpendicular anisotropy, where ferromagnetic (FM) layers are antiferromagnetically (AFM) aligned. Such systems are not affected by magnetic fi elds perpendicular to the layers until the applied fi eld becomes comparable to the AFM interlayer interaction, when a fi rst-order transition to an FM structure occurs. If a fi nite demagnetization fi eld is present, the high-fi eld FM phase is reached through a "mixed phase," existing in a fi nite range of fi elds. In this phase, AFM and FM orders coexist. [27][28][29][30] There are numerous possible arrangements of FM and AFM domains, [ 29,30 ] and consequently a very rich excitation spectrum can be anticipated. Up to now, studies of the mixed phase have almost exclusively been restricted to ac susceptibility measurements and thus to a frequency range of 0.1-100 kHz. [31][32][33][34][35] Therefore, the intriguing dynamics of the mixed phase have remained elusive.In this paper, we focus on the recently discovered layered metamagnet Cu 3 Bi(SeO 3 ) 2 O 2 Br, with kagome-like Cu layers stacked along the c -axis. [ 36 ] At T N = 27.4 K, the system develops Controllable Broadband Absorption in the Mixed Phase of MetamagnetsMatej Pregelj , * Oksana Zaharko , Andrej Zorko , Matjaž Gomilšek , Oles Sendetskyi , Axel Günther , Mykhaylo Ozerov , Sergei A. Zvyagin , Hubertus Luetkens , Christopher Baines , Vladimir Tsurkan , and Alois Loidl Materials with broad absorption bands are highly desirable for electromagnetic fi ltering and processing applications, especially if the absorption can be externally controlled. Here, a new class of broadband-absorption materials is introduced. Namely, ...

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Magnetic field modulated microwave spectroscopy across phase transitions and the search for new superconductors

Cited by 16 publications

References 132 publications

Magnetism and the absence of superconductivity in the praseodymium–silicon system doped with carbon and boron

Magnetism and the absence of superconductivity in the praseodymium–silicon system doped with carbon and boron

Search for New Superconductors: an Electro-Magnetic Phase Transition in an Iron Meteorite Inclusion at 117 K

Controllable Broadband Absorption in the Mixed Phase of Metamagnets

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