scholarly journals Coexistence of ferromagnetism, antiferromagnetism, and superconductivity in magnetically anisotropic (Eu,La)FeAs2

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Jia Yu ◽  
Congcong Le ◽  
Zhiwei Li ◽  
Lisi Li ◽  
Tong Liu ◽  
...  
Keyword(s):  
Exchange Bias ◽  
High Temperature Superconductivity ◽  
La Doping ◽  
Electronic Phase ◽  
Potential Applications ◽  
Electronic Phase Diagram ◽  
Superconducting Loop ◽  
Physical Phenomena ◽  
The Eu ◽  
Magnetic Sublattices

AbstractMaterials with exceptional magnetism and superconductivity usually conceive emergent physical phenomena. Here, we investigate the physical properties of the (Eu,La)FeAs2 system with double magnetic sublattices. The parent EuFeAs2 shows anisotropy-associated magnetic behaviors, such as Eu-related moment canting and exchange bias. Through La doping, the magnetic anisotropy is enhanced with ferromagnetism of Eu2+ realized in the overdoped region, and a special exchange bias of the superposed ferromagnetic/superconducting loop revealed in Eu0.8La0.2FeAs2. Meanwhile, the Fe-related antiferromagnetism shows unusual robustness against La doping. Theoretical calculation and 57Fe Mössbauer spectroscopy investigation reveal a doping-tunable dual itinerant/localized nature of the Fe-related antiferromagnetism. The coexistence of the Eu-related ferromagnetism, Fe-related robust antiferromagnetism, and superconductivity is further revealed in Eu0.8La0.2FeAs2, providing a platform for further exploration of potential applications and emergent physics. Finally, an electronic phase diagram is established for (Eu,La)FeAs2 with the whole superconducting dome adjacent to the Fe-related antiferromagnetic phase, which is of benefit for seeking underlying clues to high-temperature superconductivity.

scholarly journals Electronic phase diagram of valence-controlled cyanide:Na0.84−δCo[Fe(CN)6]0.71⋅3.8H2O(0≤δ≤0.61)

2008 ◽  
Vol 77 (22) ◽  
Author(s):  
F. Nakada ◽  
H. Kamioka ◽  
Y. Moritomo ◽  
J. E. Kim ◽  
M. Takata
Keyword(s):  
Phase Diagram ◽  
Electronic Phase ◽  
Electronic Phase Diagram

scholarly journals Modulation of Ferroelectric and Optical Properties of La/Co-Doped KNbO3 Ceramics

Nanomaterials ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 2273
Author(s):  
Xue Zhang ◽  
Ruijuan Qi ◽  
Shangwei Dong ◽  
Shuai Yang ◽  
Chengbin Jing ◽  
...  
Keyword(s):  
Ferroelectric Properties ◽  
Cubic Phase ◽  
Bandgap Engineering ◽  
La Doping ◽  
Co Doping ◽  
Extrinsic Defect ◽  
Potential Applications ◽  
Defect Levels ◽  
Microscopic Morphology ◽  
Co Doped

The phase transition, microscopic morphology and optical and ferroelectric properties are studied in a series of La- and Co-doped KNbO3-based ceramics. The results show that the doping induces the transformation from the orthorhombic to the cubic phase of KNbO3, significantly reduces the optical bandgap and simultaneously evidently improves the leakage, with a slight weakening of ferroelectric polarization. Further analysis reveals that (i) the Co doping is responsible for the obvious reduction of the bandgap, whereas it is reversed for the La doping; (ii) the slight deterioration of ferroelectricity is due to the doping-induced remarkable extrinsic defect levels and intrinsic oxygen vacancies; and (iii) the La doping can optimize the defect levels and inhibit the leakage. This investigation should both provide novel insight for exploring the bandgap engineering and ferroelectric properties of KNbO3, and suggest its potential applications, e.g., photovoltaic and multifunctional materials.

scholarly journals The Effect of Ionising Radiation on the Luminescence Properties of Fluoroperovskites

2021 ◽  
Author(s):  
◽  
Joseph Schuyt
Keyword(s):  
Energy Levels ◽  
Thermal Quenching ◽  
Ionising Radiation ◽  
Luminescence Properties ◽  
Readout System ◽  
Tissue Equivalent ◽  
Potential Applications ◽  
Radiation Induced ◽  
Medical Dosimetry ◽  
Physical Phenomena

<p>The luminescence of crystalline compounds can be used to monitor many physical phenomena, including doses of ionising radiation. Optically stimulated luminescence (OSL), thermoluminescence (TL), and radiophotoluminescence (RPL) have been successfully employed in dosimetry. However, few materials possess both the structural and luminescence properties required for medical dosimetry. This thesis aimed to investigate the luminescence features of the class of compounds known as fluoroperovskites. Emphasis was placed on studying the effects of irradiation on the luminescence properties, such that the compounds could be evaluated regarding potential applications in clinical dosimetry. Samples were primarily characterised using photoluminescence (PL), radioluminescence (RL), OSL, RPL, TL, and transmittance spectroscopy.  OSL was observed in the majority of samples due to the existence of electron trapping F-type centres. F-centre/Mn complexes were observed in all AMgF3:Mn compounds after irradiation and the energy levels of the complexes in each compound were experimentally determined. The most promising potential dosimeter host material was the near tissue-equivalent NaMgF3. When doped with Mn2+, the compound exhibited RPL via the formation of F-centre/Mn complexes and OSL via several trapping centres. The RPL could be probed independently to the OSL such that the compound could function as a hybrid OSL/RPL dosimeter. In the NaMgF3:Ln compounds, RPL occurred via the radiation-induced reduction Ln3+ → Ln2+ for Ln = Sm, Dy, and Yb. The reduction Sm3+ → Sm2+ was highly stable and could be non-destructively probed independently to the OSL. The Sm doped compound also exhibited radiation-induced conductivity that could be coupled with the RL, such that the compound could function as a real-time hybrid optical/electrical dosimeter. Charge kinetics, thermal quenching, and binding energy models were developed and applied to the compounds.   Finally, a two-dimensional readout system was designed and constructed. The capabilities of the system were evaluated using the OSL of NaMgF3:Eu and NaMgF3:Mn. Sensitivities to doses from < 10 mGy to > 1 Gy were obtained along with sub-millimetre spatial resolutions.</p>

Electronic phase diagram of La2−xSrxCuO4

2004 ◽  
Vol 65 (8-9) ◽  
pp. 1381-1390 ◽  
Author(s):  
Migaku Oda ◽  
Naoki Momono ◽  
Masayuki Ido
Keyword(s):  
Phase Diagram ◽  
Electronic Phase ◽  
Electronic Phase Diagram

scholarly journals The electronic phase diagrams of the Eu(Fe0.81Co0.19)2As2superconductor

2012 ◽  
Vol 14 (7) ◽  
pp. 073052 ◽  
Author(s):  
Vinh Hung Tran ◽  
Zbigniew Bukowski ◽  
Lan Maria Tran ◽  
Andrzej J Zaleski
Keyword(s):  
Phase Diagrams ◽  
Electronic Phase ◽  
The Eu

Engineering Design as Research

2012 ◽  
pp. 1766-1779
Author(s):  
Timothy L.J. Ferris
Keyword(s):  
Decision Making ◽  
Research Projects ◽  
Design Work ◽  
Engineering Research ◽  
Is Research ◽  
New Knowledge ◽  
Potential Applications ◽  
Actual Design ◽  
Physical Phenomena ◽  
The Impact

Research is defined as an activity that creates new knowledge. This is often misunderstood in the engineering community as necessarily requiring a scientific contribution that advances the theory of some matter related to engineering materials or processes. Consequently, typical engineering research projects investigate physical phenomena thought likely to be interesting in potential applications or to describe the characteristics of processes used in engineering work. The results of such projects provide a fragmented, abstracted view of the phenomena investigated, which is difficult to use in engineering decision making related to contextualised situations. This chapter shows how the actual design of engineered artefacts is research because it provides knowledge of the impact of the integration of various elements of existing knowledge, which demonstrates the properties of the designs achieved through the design work and leads to discovery of solutions to the various challenges of integration discovered through the project which attempts to achieve the integration.

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