Search

Your search keyword '"Xia, Yanfang"' showing total 178 results
Start Over Author "Xia, Yanfang"
178 results on '"Xia, Yanfang"'

2. The Effect of Ionic Spin on Multiferroic of Orthorhombic Perovskite

Author

Gao, Kaiyang, Shen, Jiyu, Lu, Zeyi, Mo, Jiajun, Liu, Guoqing, Wu, Zhongjin, Gong, Chenying, Xie, Dong, Xia, Yanfang, and Liu, Min

Subjects
Condensed Matter - Materials Science, Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

To investigate the influence of ion spin on the coupling between ferromagnetism and ferroelectricity in type II multiferroic perovskite, we prepared the multiferroic perovskite Er0.9La0.1Cr0.8Fe0.2O3 (ELCFO) using the sol-gel method, and explored the macroscopic magnetic properties of ELCFO through M\"ossbauer spectrum and magnetic testing. The thermal magnetic curve was analyzed to examine the state and change of each ionic spin in the ELCFO system at different temperature ranges, and the role of ionic spin in the coupling between ferromagnetism and ferroelectricity was investigated. This study provides a theoretical basis for further research on multiferroic perovskites and has practical implications.

Published
2023

6. Unraveling the spin reorientation process in rare earth perovskite PrFe0.1Cr0.9O3

Author

Shen, Jiyu, Mo, Jiajun, Lu, Zeyi, Gong, Chenying, Wu, Zongjin, Gao, Kaiyang, Liu, Min, and Xia, Yanfang

Subjects
Condensed Matter - Materials Science
Abstract

Ultrafast spin control plays a pivotal role in condensed matter physics. In this study, we analyzed the macroscopic magnetization of the PrFe0.1Cr0.9O3 system by molecular field model fitting. And the whole process of system spin reorientation is accurately calculated in the fitting process. It is found that, unlike the rare-earth perovskites we have previously studied, PrFe0.1Cr0.9O3 exhibits spin-reversion properties during the reorientation process. This research will lay a theoretical foundation for precise spin control in the future., Comment: arXiv admin note: text overlap with arXiv:2207.03220

Published
2022
Full Text
View/download PDF

7. Special spin behavior of rare earth ions at the A site of polycrystalline ErFe1-xCrxO3 (x = 0.1, 0.9)

Author

Shen, Jiyu, Mo, Jiajun, Lu, Zeyi, Wu, Zhongjin, Gong, Chenying, Gao, Kaiyang, Zheng, Pinglu, Liu, Min, and Xia, Yanfang

Subjects
Condensed Matter - Materials Science
Abstract

Thermally induced spin control is one of the main directions for future spin devices. In this study, we synthesized single-phase polycrystalline ErFe1-xCrxO3 and combined the magnetization curves and M\"ossbauer spectra to determine the macroscopic magnetism at room temperature. The magnetization of the system at various temperatures is well simulated by molecular field theory. And it is found that under the DM interaction, not only the B-site ions undergo a reorientation process, but the spins of the A-site ions also change at the same time. The effective spin is defined as the projection of Er3+ on the Fe3+/Cr3+ spin plane, and the whole reorientation process is obtained by fitting. This study will complement the actual process of ErFe1-xCrxO3 spin reorientation and will lay a theoretical foundation for the fabrication of future spin-controlled devices.

Published
2022

8. Unraveling the nature of thermally induced spin reorientation in NdFe1-xCrxO3

Author

Shen, Jiyu, Mo, Jiajun, Lu, Zeyi, Huang, Huilin, Gong, Chenying, Long, Yi, Arramel, Xia, Yanfang, Liu, Min, and Jiang, Jizhou

Subjects
Condensed Matter - Materials Science
Abstract

Understanding spin control mechanisms is an important part of condensed matter physics and the theoretical basis for designing spintronic devices. In this letter, based on four-sublattices molecular field theory, we propose that the underlying NdFe1-xCrxO3 magnetic mechanism is driven by spin reorientation sensitive to temperature. The actual coupling angular momentum, angle between the Nd3+ and Cr3+/Fe3+ moments at the given temperature is realized via the Nd3+ magnetic moment projection onto the Cr3+/Fe3+ plane. As the temperature increases, the angle between the moment of Nd3+ and the moment of Cr3+/Fe3+ decreases monotonically. In this work, the magnetic mechanism of NdFe1-xCrxO3 (x=0.1, 0.9), the close relationship between A/B angle and temperature are presented, which laid a theoretical foundation for the design of new multifunctional magnetic materials.

Published
2022

9. Unraveling Thermally Induced Spin reorientation of Strongly Disordered NdFe0.5Cr0.5O3 System

Author

Shen, Jiyu, Mo, Jiajun, Lu, Zeyi, Gong, Chenying, Gao, Kaiyang, Shi, Ke, Yu, Lizhou, Chen, Yan, Liu, Min, and Xia, Yanfang

Subjects
Physics - Applied Physics, Condensed Matter - Materials Science
Abstract

Sophisticated spin instruments require high-precision spin control. In this study, we accurately study the intrinsic magnetic properties of the strongly disordered system NdFe0.5Cr0.5O3 through molecular field models combined with ASD theory. The three constituent sub-magnetic phases of the system are separated, and their magnetization contributions are calculated separately. Fitting the angle of the A/B magnetic moment at a given temperature, the reorientation temperature point and temperature dependence of different magnetic phases are obtained. This research will provide a very good theoretical support for studying complex disordered systems and applying high-precision spin control and lay a foundation for the design of new functional materials.

Published
2022

10. The distribution of B-site in the perovskite for a d5-d3 superexchange system studied with Molecular field theory and Monte Carlo simulation

Author

Mo, Jiajun, Liu, Min, Xu, Shiyu, Zhang, Qinghang, Shen, Jiyu, Xia, Puyue, Xia, Yanfang, and Jiang, Jizhou

Subjects
Condensed Matter - Materials Science, Physics - Atomic and Molecular Clusters
Abstract

The B-site disorder in the d5 - d3 system of perovskites has been analyzed with molecular field theory and Monte Carlo method. The model is applicable to RFe1-pCrpO3 at any p value. When the saturation magnetization MS and phase transition temperature TP are known, a model can be built to calculate the order or disorder distribution of lattice B-sites. We analyze the case that the Fe-Cr superexchange is antiferromagnetic and ferromagnetic coupling respectively. The simulation result shows that the theoretical calculation formula is suitable for the calculation of different B-site distribution. Through the simulation, we find that when the x and y are large, the system will appear obvious long-range order. The DM interaction has a certain influence on the saturation magnetization. Via calculation, we found that the distribution states of Fe and Cr do not always conform to the uniform distribution but rather exhibit an effect that reduces the Fe-Fe clustering. The establishment of this model offers an explanation for several previously contentious issues, e.g., what is the phase transition temperature range of double perovskite, and why the different phase transition temperatures with the same doping proportion. It provides theoretical guidance for the design of functional materials with an arbitrary phase transition temperature.

Published
2022
Full Text
View/download PDF

23. Effect of Co doping on the structure and magnetic properties of Bi0.8Ba0.2FeO3 nanoparticles.

Author

Wu, Zhongjin, Liu, Guoqing, Lu, Zeyi, Gao, Kaiyang, Wang, Changyang, Liu, Min, and Xia, Yanfang

Subjects
MAGNETIC structure, MAGNETIC properties, NANOPARTICLES, LATTICE constants, SPACE groups
Abstract

A series of Bi 0. 8 Ba 0. 2 Fe 1 − x CoxO3 (x = 0. 0 0 , 0.05, 0.10, and 0.15) samples were synthesized using the tartaric acid modified sol–gel method. The crystal structure of the prepared samples was analyzed by XRD, and the samples co-doped with Ba and Co were all rhombohedral distorted structures with the R3c space group. With an increase in the doping amount, a reduction in lattice parameters was observed along with crystallite sizes consistently being below 62 nm. Mössbauer spectral analysis at room temperature reveals a good fit with two sextets and a doublet, all attributed to the Fe 3 + state. This suggests that the charge balance within the samples is maintained through the generation of oxygen vacancies in the system. The hysteresis loops of all samples revealed the weak ferromagnetic of the Co-doped Bi 0. 8 Ba 0. 2 FeO3 nanoparticles. With the increase in Co doping, the magnetic parameters such as saturation magnetization and coercive field significantly improved. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

24. Pavlovian-to-Instrumental Transfer after Human Threat Conditioning

Author

Xia, Yanfang, Gurkina, Angelina, and Bach, Dominik R.

Abstract

Threat conditioning is a common associative learning model with translational relevance. How threat-conditioned cues impact on formally unrelated instrumental behavior in humans is not well known. Such an effect is known as Pavlovian-to-instrumental transfer (PIT). While PIT with aversive primary Pavlovian reinforcers is established in nonhuman animals, this is less clear in humans, where secondary reinforcers or instructed instrumental responses are most often investigated. We modified an existing human PIT procedure to include primary reinforcers. Participants first learned to obtain (or avoid losing) appetitive instrumental reinforcement (chocolate) by appropriate approach or avoidance actions. They either had to act (Go) or to withhold an action (NoGo), and in the Go condition either to approach a reward target to collect it or to withdraw from the reward target to avoid losing it. Then they learned to associate screen color (CS) with aversive Pavlovian reinforcement (electric shock US). In the transfer phase, we conducted the instrumental task during the presence of Pavlovian CS. In a first experiment, we show that the aversive Pavlovian CS+, compared to CS--, increased response rate in Go-Withdraw trials, i.e., induce conditioned facilitation of avoidance responses. This finding was confirmed in a second and independent experiment with an increased number of Go-Withdraw trials. Notably, we observed no appreciable conditioned suppression of approach responses. Effect size to distinguish CS+/CS--in Go-Withdraw trials was d = 0.42 in the confirmation sample. This would require n = 37 participants to demonstrate threat learning with 80% power. Thus, the effect size is on a practically useful scale although smaller than for model-based analysis of autonomic measures. In summary, our results indicate conditioned facilitation of formally unrelated instrumental avoidance behavior in humans and provide a novel behavioral threat learning measure that requires only key presses.

Published
2019
Full Text
View/download PDF

31. Opioid modulation of ventral pallidal afferents to ventral tegmental area neurons.

Author

Hjelmstad, Gregory, Xia, Yanfang, Fields, Howard, and Margolis, Elyssa

Subjects
Analgesics, Opioid, Animals, Channelrhodopsins, Dopaminergic Neurons, Enkephalin, Ala(2)-MePhe(4)-Gly(5)-, GABAergic Neurons, Globus Pallidus, Inhibitory Postsynaptic Potentials, Male, Neural Pathways, Neurons, Optogenetics, Photic Stimulation, Rats, Rats, Sprague-Dawley, Receptors, Opioid, mu, Ventral Tegmental Area
Abstract

Activation of mu opioid receptors within the ventral tegmental area (VTA) can produce reward through the inhibition of GABAergic inputs. GABAergic neurons in the ventral pallidum (VP) provide a major input to VTA neurons. To determine the specific VTA neuronal targets of VP afferents and their sensitivity to mu opioid receptor agonists, we virally expressed channel rhodopsin (ChR2) in rat VP neurons and optogenetically activated their terminals in the VTA. Light activation of VP neuron terminals elicited GABAergic IPSCs in both dopamine (DA) and non-DA VTA neurons, and these IPSCs were inhibited by the mu opioid receptor agonist DAMGO. In addition, using a fluorescent retrograde marker to identify VTA-projecting VP neurons, we found them to be hyperpolarized by DAMGO. Both of these actions decrease GABAergic input onto VTA neurons, revealing two mechanisms by which endogenous or exogenous opioids can activate VTA neurons, including DA neurons.

Published
2013

40. Effect of the Matrix Metalloproteinase Inhibitor Doxycycline on Human Trace Fear Memory

Author

Wehrli, Jelena M, Xia, Yanfang, Offenhammer, Benjamin, Kleim, Birgit, Müller, Daniel, Bach, Dominik R, University of Zurich, and Bach, Dominik R

Subjects
10093 Institute of Psychology, General Neuroscience, 2800 General Neuroscience, General Medicine, 150 Psychology
Abstract

Learning to predict threat is of adaptive importance, but aversive memory can also become disadvantageous and burdensome in clinical conditions such as posttraumatic stress disorder (PTSD). Pavlovian fear conditioning is a laboratory model of aversive memory and thought to rely on structural synaptic reconfiguration involving matrix metalloproteinase (MMP)9 signaling. It has recently been suggested that the MMP9-inhibiting antibiotic doxycycline, applied before acquisition training in humans, reduces fear memory retention after one week. This previous study used cued delay fear conditioning, in which predictors and outcomes overlap in time. However, temporal separation of predictors and outcomes is common in clinical conditions. Learning the association of temporally separated events requires a partly different neural circuitry, for which the role of MMP9 signaling is not yet known. Here, we investigate the impact of doxycycline on long-interval (15 s) trace fear conditioning in a randomized controlled trial with 101 (50 females) human participants. We find no impact of the drug in our preregistered analyses. Exploratorypost hocanalyses of memory retention suggested a serum level-dependent effect of doxycycline on trace fear memory retention. However, effect size to distinguish CS+/CS− in the placebo group turned out to be smaller than in previously used delay fear conditioning protocols, which limits the power of statistical tests. Our results suggest that doxycycline effect on trace fear conditioning in healthy individuals is smaller and less robust than anticipated, potentially limiting its clinical application potential.

Published
2023

41. MinAv: SCR, ECG, respiration, startle eyeblink EMG and eyetracking measurements in an RCT using minocycline/placebo during configural fear conditioning and retention

Author

Xia, Yanfang, Wehrli, Jelena, Abivardi, Aslan, Hostiuc, Madalina, Kleim, Birgit, and Bach, Dominik R

Abstract

This dataset contains skin conductance responses (SCR), electrocardiogram (ECG), respiration, electromyogram (EMG), pupil size (PSR), and gaze coordinates measurements for 107 healthy individuals participating in a double-blind, placebo-controlled, randomized trial using a Pavlovian differential configural fear conditioning experiment with 3 sessions. The placebo group (n=54) includes 35 females and 19 males, aged 23.06 +/- 2.91 years; the minocycline (n=53) group includes 35 females and 18 males, aged 23.28 +/- 3.76 years. All participants were screened in a health check-up before session 1. CSs were five static room images presented full-screen, one of which served as CS+, coupled with US, and the other four as CS-. The US was a 0.5-s electric shock of 250 square pulses with a 10% duty cycle, delivered with a constant current stimulator on participants' dominant forearm through a pin-cathode/ring-anode configuration. SOA between the CS onset and the US was 7.0 s. Participants underwent the conditioning task with CSs (CS+ 83% reinforced) and US delivery in session 1 with 4 blocks and were tested in a recall/extinction task one week later in session 2 with 4 blocks, with CS and auditory startle probe (ST) delivered 7.0 s after CS onset via headphones (ca. 102 dB, 40 ms duration). No US was delivered during session 2. Session 3 (relearning) immediately followed session 2 and had the same structure as session 1 (CS+ coupled with US, 83% reinforcement) but contained only 2 blocks. Participants in the minocycline group received a single oral dosage of 200 mg minocycline around 120 min before the start of fear conditioning in session 1, while the placebo group received mannitol. No drug was administered in sessions 2 and 3. The ITI was drawn on each trial uniformly at random between 7.5 to 10.5 s. The blocks within each session were recorded in succession with self-paced breaks.

Published
2023
Full Text
View/download PDF

43. Mössbauer and Magnetic Properties Investigation of REFe0.5Cr0.5O3 (RE=La, Y) Perovskite.

Author

Yang, Jiayun, Cao, Huanhuan, Lu, Zeyi, Mo, Jiajun, Zhou, Yang, Gao, Kaiyang, Xue, Xinhao, Xia, Yanfang, and Liu, Min

Subjects
MAGNETIC properties, MAGNETIZATION reversal, MAGNETIC anisotropy, MAGNETIC moments, PEROVSKITE, MAGNETIC entropy, IRON
Abstract

The synthesis of REFe0.5Cr0.5O3 (RE = La, Y) using the sol–gel method is focused and their structural differences are investigated. The results of X‐ray diffraction show that the change of ion radius at position A leads to varying degrees of octahedral distortion and spatial group structure. The scanning electron microscopy analysis reveals micron‐level particles with clear boundaries, while energy‐dispersive X‐ray spectroscopy and room temperature Mössbauer spectra indicate the presence of Fe/Cr clusters in the sample and the transitional valence of iron. Disorder in the B position leads to a saturation moment that is lower than the theoretical value. The thermomagnetic profile shows a reversal of magnetization due to the interaction between the single‐ion magnetic anisotropy and the antisymmetric Dzyaloshinskii–Moriya (DM) interaction, with a broader peak is observed due to cluster formation. The difference in negative magnetic field is due to the difference in net magnetic moment caused by different DM intensities. [ABSTRACT FROM AUTHOR]

Published
2023
Full Text
View/download PDF

50. Context_FC

Author

Xia, Yanfang, Wehrli, Jelena, and Bach, Dominik

Abstract

this project stores experimental and analysis scripts of context fear conditioning project, including CTX2, CTX3, CFG, and CFG2.

Published
2022
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results