拉拉铁氧化物-铜-金-铀(IOCG)矿床石英-磁铁矿地质温度计

拉拉矿床的形成经历了区域变质成矿期和热液成矿期,前人对拉拉矿床的区域变质峰期温度以及热液成矿期的成矿温度进行了研究,但对于区域变质期的成矿温度的研究资料相对不足。利用区域变质成矿期形成共生矿物组合磁铁矿-石英,采用石英-磁铁矿地质温度计,获得区域变质成矿期的成矿温度为450℃～500℃。并结合前人研究结果,认为拉拉矿床的形成是区域变质峰期之后的产物。

温度变化对电磁低压铸造磁感应强度的影响研究

模拟电磁泵工作状态下电磁铁的工作情况,在电磁铁上放置加热保温装置,内置热电偶进行温度监控,测量电磁铁在不同温度下磁隙间的磁感应强度。根据实验结果得到,对于同一励磁电流值,随着温度的升高,磁感应强度也增大,并对结果进行数学回归法分析,得出电磁泵实际工作下,即励磁电流为60A的情况下的磁感应强度By与温度T之间的函数关系式,提高了该项技术的可知性。

S7-1200在医用重离子加速器上的应用

重离子加速器作为新的医疗设备对于肿瘤的治疗效果明显。本文针对医用重离子加速器真空与励磁系统的控制要求,采用西门子S7-1200现场控制器,通过串行通讯模块对现场的功率、电压、电流、转速、真空度以及各种磁铁温度等设备数据进行读写、解析,并在上位机实时显示与存储,最终实现了对重离子加速器真空系统及磁铁温度的检测控制。实际应用表明:该系统运行稳定,性能良好。

石英—磁铁矿地质温度计在拉拉铁氧化物—铜—金—铀(IOCG)矿床的应用

磁铁矿是拉拉矿床区域变质成矿期的主要金属矿物,前人对拉拉矿床的区域变质峰期温度以及成矿温度进行了研究。利用石英—磁铁矿地质温度计研究得出:磁铁矿的是在变质峰期后随着温压条件的改变而形成,温度在450~500℃之间。结合前人对压力的研究,得出区域变质作用应为高绿片岩相。

Temperature Dependence of Exchange Bias and Coercivity in Ferromagnetic Layer Coupled with Polycrystalline Antiferromagnetic Layer

The temperature dependence of exchange bias and coercivity in a ferromagnetic layer coupled with an antiferromagnetic layer is discussed.In this model,the temperature dependence comes from the thermal instability of the system states and the temperature modulated relative magnetic parameters.Morever,the thermal fluctuation of orientations of easy axes of antiferromagnetic grains at preparing has been considered.From the present model,the experimental results can be illustrated qualitatively for available magnetic parameters.Based on our discussion,we can conclude that soft ferromagnetic layer coupled by hard antiferromagnetic layer may be very applicable to design magnetic devices.In special exchange coupling,we can get high exchange bias and low coercivity almost independent of temperature for proper temperature ranges.

Calcium ferrite formation characteristic during iron ore sintering with different oxygen atmospheres

It is generally known that the large formation amount of calcium ferrite is favorable for the iron ore sintering. The effects of sintering temperature and O2 content of inlet gas on the calcium ferrite formation characteristic of typical iron ores, including hematite, limonite, specularite and magnetite, were investigated. And the effect of O2 content on the microstructure of the roasted briquettes was also studied in detail. The results show the amount of calcium ferrite initially increases then decreases with the increase of the sintering temperature. The temperature of maximum calcium ferrite generation amount is determined as follows： for hematite and limonite it is 1275 ~C, whereas for specularite and magnetite, 1250℃. The maximum contents of calcium ferrite for hematite, limonite, specularite and magnetite under the optimal sintering temperature are 73%, 82%, 67% and 63%, respectively. Increasing O2 content of the airflow is advantageous to the formation of calcium ferrite. Relatively, the effect of O2 content on the calcium ferrite formation of magnetite is the most pronounced, while O2 content of inlet gas has little effect on the calcium ferrite formation of limonite.

An experiment discovery about gravitational force changes in materials due to temperature variation

The authors discovered in first time that the weight of materials or its gravitational force by earth related to its temperature and its ferromagnetism. An experiment was designed to elevate the temperatures of six different materials （Au, Ag, Cu, Fe, Al, Ni） up to 600 ℃and precisely measured their weights. It is found all the materials weigh about 0.33 ‰ - 0. 82 ‰ less. For example the weight of silver sample weighted by a precision electronic scale in a manner of special design decreases about 0.8 ‰, when its temperature is elevated to 600 ℃. Thus different metals＇ gravitational forces or weights are adjusted with temperature variation.

Room Temperature Ferromagnetism in Ga1-xHoxN （x=0.0 and 0.05） Diluted Magnetic Semiconductor Thin Films

Holmium doped GaN diluted magnetic semiconductor thin films have been prepared by thermal evaporation technique and subsequent ammonia annealing. X-ray diffraction mea- surements reveal all peaks belong to the purely hexagonal wurtzite structure. Surface mor- phology and composition analysis were carried out by scanning electron microscopy and energy dispersive spectroscopy respectively. The room temperature ferromagnetic proper- ties of Gal-xHoxN （x=0.0, 0.05） films were analyzed using vibrating sample magnetometer at room temperature. Magnetic measurements showed that the undoped films （i.e. GaN） exhibited diamagnetic behavior, while the Ho-doped （Gao.95Hoo.05N） film exhibited a ferro- magnetic behavior.

Magnetic Properties of Ferromagnetic Double Layers with Ferrimagnetic Interlayer Coupling at Zero Temperature

Spin-wave theory is used to study magnetic properties of ferromagnetic double layers with a ferrimagnetic interlayer coupling at zero temperature. The spin-wave spectra and four sublattices magnetizations and internal energy are calculated by employing retarded Green function technique. The sublattice magnetizations at ground state are smaller than their classical values, owing to the zero-point quantum fluctuations of the spins.

Preparation of water-soluble magnetic nanoparticles with controllable silica coating

This work provides a general method for preparing monodisperse, water-soluble and paramagnetic magnetic nanoparticles which are easy to be modified. Firstly, magnetic silica with core-shell structure was prepared according to a previous work. Then, the magnetic silica was treated with alkali solution to afford magnetic nanoparticles. With the increase of calcination temperature for the preparation of magnetic silica, the crystallinity and the magnetic responsibility of magnetic silica strengthened, meanwhile, the corresponding magnetic nanoparticles kept monodisperse without any aggregation. The magnetic nanoparticles are comprised of cobalt ferrite and a silica coating. The silica coating on the cobalt ferrite facilitates the magnetic nanoparticles well-dissolved and monodisperse in water, and easilv modified.

Calculation of Half-Metal, Debye and Curie Temperatures of Co_2 VAl Compound: First Principles Study

By FP-LAPW calculations, the structural, elastic, Debye and Curie temperatures, electronic and magnetic properties of Co2 VAl are investigated. The results indicate that Ferromagnetic （FM） phase is more stable than Anti- Ferromagnetic （AFM） and Non-magnetic （NM） ones. In addition, C11-C12 〉 0, C44 〉 0, and B 〉 0 so Co2 VAl is an elastically stable material with high Debye temperature. Also, the BIG ratio exhibits a ductility behavior. The relatively high Curie temperature provides it as a favorable material for spintronic application. It＇s electronic and magnetic properties are studied by GGA ＋U approach leading to a 100% spin polarization at Fermi level.

Enhancement of the Curie temperature of ferromagnetic semiconductor(Ga,Mn)As

In this review article,we review the progress made in the past several years mainly regarding the efforts devoted to increasing the Curie temperature(T C) of(Ga,Mn)As,which is most widely considered as the prototype ferromagnetic semiconductor.Heavy Mn doping,nanostructure engineering and post-growth annealing which increase T C are described in detail.

Protonation induced high-T_c phases in iron-based superconductors evidenced by NMR and magnetization measurements

Chemical substitution during growth is a well-established method to manipulate electronic states of quantum materials, and leads to rich spectra of phase diagrams in cuprate and iron-based superconductors. Here we report a novel and generic strategy to achieve nonvolatile electron doping in series of(i.e.11 and 122 structures) Fe-based superconductors by ionic liquid gating induced protonation at room temperature. Accumulation of protons in bulk compounds induces superconductivity in the parent compounds, and enhances the Tclargely in some superconducting ones. Furthermore, the existence of proton in the lattice enables the first proton nuclear magnetic resonance(NMR) study to probe directly superconductivity. Using Fe S as a model system, our NMR study reveals an emergent high-Tcphase with no coherence peak which is hard to measure by NMR with other isotopes. This novel electric-fieldinduced proton evolution opens up an avenue for manipulation of competing electronic states(e.g.Mott insulators), and may provide an innovative way for a broad perspective of NMR measurements with greatly enhanced detecting resolution.

Quantum discord in three-spin XXZ chain with three-spin interaction

Quantum discord, as a kind of measurement of quantum correlation, has received much attention since it was introduced. This paper focuses on studying quantum discord in three-spin XXZ chain with three-spin interaction. The effects of all kinds of pa- rameters on quantum discord in the ferromagnetic region J=-I are studied. The three-spin interaction may increase the value of quantum discord between two spins, while the anisotropy may decrease the value. In addition, the regrowth of quantum discord with temperature is found in the model. For zero temperature, quantum phase transition is existent.

Air-stable diradical dications with ferromagnetic interaction exceeding the thermal energy at room temperature: from a monomer to a dimer

Two tetraazacyclophane dications(1^(2+) and 2^(2+)) with different remote substituents have been synthesized, isolated and characterized.Their electronic structures and physical property were studied by various spectroscopic techniques, single crystal X-ray diffraction,super conducting quantum interference device(SQUID) measurements and theoretical calculations. The dications have triplet ground states with ferromagnetic interaction exceeding the thermal energy at room temperature. The solid-state structures of these species were tunable by substituent effect, with 1^(2+) as a monomer and 2^(2+) as a dimer.

The melilite-type compound (Sr_(1-x),A_x)_2MnGe_2S_6O(A=K,La) being a room temperature ferromagnetic semiconductor

The seeking of room temperature ferromagnetic semiconductors, which take advantages of both the charge and spin degrees of freedom of electrons to realize a variety of functionalities in devices integrated with electronic, optical, and magnetic storage properties, has been a long-term goal of scientists and engi- neers. Here, by using the spin-polarized density functional theory calculations, we predict a new series of high temperature ferromagnetic semiconductors based on the melilite-type oxysulfide Sr2MnGe2S60 through hole （K） and electron （La） doping. Due to the lack of strong antiferromagnetic superexchange between Mn ions, the weak antiferromagnetic order in the parent compound Sr2MnGe2S60 can be sup- pressed easily by charge doping with either p-type magnetic order. At a doping concentration of or n-type carriers, giving rise to the expected ferro- 25%, both the hole-doped and electron-doped compounds can achieve a Curie temperature （To） above 300 K. The underlying mechanism is analyzed. Our study provides an effective approach for exploring new types of high temperature ferromagnetic semiconductors.

Diluted ferromagnetic semiconductor(LaCa)(ZnMn)SbO isostructural to “1111” type iron pnictide superconductors

We report discovery of ferromagnetism in(LaCa)(ZnMn)SbO isostructural to the well-studied iron-based superconductor LaFeAs(O1 xFx).Spin is induced by partial substitution of Mn2+for Zn2+,while charge is induced by substitution of Ca2+for La3+within the parent compound LaZnSbO.Ferromagnetism with Curie temperature(TC)is observed up to 40 K at the spin doping 0.15 by introducing Mn2+into the Zn2+sites for(La0.95Ca0.05)(Zn1 xMnx)SbO.The Hall coefficient measurement indicates p-type carrier for(La0.95Ca0.05)(Zn0.9Mn0.1)SbO with concentration of n^1020cm 3showing anomalous Hall effect below TC.

Quantum Correlation in Three-Qubit Heisenberg Model with Dzyaloshinskii-Moriya Interaction

We investigate the pairwise thermal quantum discord in a three-qubit XXZ model with Dzyaloshinskii-Moriya (DM) interaction. We find that the effects of DM interaction on antiferromagnetic system is distinct from that of ferromagnetic system. The magnetic field supplemented with DM term contribute to enhance the range of quantum discord. It is revealed that the situations where quantum discord fails to indicate a sudden change of groundstate at finite temperature though indicating such a sudden change of groundstate at zero temperature. Dynamics of pairwise thermal quantum discord is considered as well. Thermal quantum discord vanishes in asymptotic limit regardless of its initial values, however, thermal entanglement suddenly disappears in finite time.

Frustrated ferromagnetic transition in AB-stacked honeycomb bilayer

In two-dimensional(2D) ferromagnets, anisotropy is essential for the magnetic ordering as dictated by the Mermin-Wagner theorem. But when competing anisotropies are present, the phase transition becomes nontrivial. Here, utilizing highly sensitive susceptometry of scanning superconducting quantum interference device microscopy, we probe the spin correlations of ABC-stacked Cr Br3under zero magnetic field. We identify a plateau feature in susceptibility above the critical temperature(TC) in thick samples.It signifies a crossover regime induced by the competition between easy-plane intralayer exchange anisotropy versus uniaxial interlayer anisotropy. The evolution of the critical behavior from the bulk to 2D shows that the competition between the anisotropies is magnified in the reduced dimension. It leads to a strongly frustrated ferromagnetic transition in the bilayer with fluctuation on the order of TC, which is distinct from both the monolayer and the bulk. Our observation demonstrates unconventional 2D critical behavior on a honeycomb lattice.

Observation of a bi-critical point between antiferromagnetic and superconducting phases in pressurized single crystal Ca0.73La0.27FeAs2

One of the most strikingly universal features of the high-temperature superconductors is that the super- conducting phase emerges in the close proximity of the antiferromagnetic phase, and the interplay between these two phases poses a long-standing challenge. It is commonly believed that, as the antifer- romagnetic transition temperature is continuously suppressed to zero, there appears a quantum critical point, around which the existence of antiferromagnetic fluctuation is responsible for the development of the superconductivity. In contrast to this scenario, we report the observation of a bi-critical point identified at 2,88 GPa and 26.02 K in the pressurized high-quality single crystal Cao.73Lao.27FeAs2 by com- plementary in-situ high pressure measurements. At the critical pressure, we find that the antiferromag- netism suddenly disappears and superconductivity simultaneously emerges at almost the same temperature, and that the external magnetic field suppresses the superconducting transition temperature but hardly affects the antiferromagnetic transition temperature.