اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدAdiabatic measurements of magneto-caloric effects in pulsed high magnetic fields up to 55 T
136
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
Magneto-caloric effects (MCEs) measurement system in adiabatic condition is proposed to investigate the thermodynamic properties in pulsed magnetic fields up to 55 T. With taking the advantage of the fast field- sweep rate in pulsed field, adiabatic measurements of MCEs were carried out at various temperatures. To obtain the prompt response of the thermometer in the pulsed field, a thin film thermometer is grown directly on the sample surfaces. The validity of the present setup was demonstrated in the wide temperature range through the measurements on Gd at about room temperature and on Gd3Ga5O12 at low temperatures. The both results show reasonable agreement with the data reported earlier. By comparing the MCE data with the specific heat data, we could estimate the entropy as functions of magnetic field and temperature. The results demonstrate the possibility that our approach can trace the change in transition temperature caused by the external field.
قيم البحث
اقرأ أيضاً
Single shot x-ray diffraction (XRD) experiments have been performed with a x-ray free electron laser (XFEL) under pulsed high magnetic fields up to 16 T generated with a nondestructive minicoil. The antiferromagnetic insulator phase in a perovskite m
anganaite, Pr$_{0.6}$Ca$_{0.4}$MnO$_{3}$, is collapsed at a magnetic field of $approx 8$ T with an emergence of the ferromagnetic metallic phase, which is observed via the accompanying lattice changes in a series of the single shot XRD. The feasibility of the single shot XRD experiment under ultrahigh magnetic fields beyond 100 T is discussed, which is generated with a portable destructive pulse magnet.
We have measured the magnetization and specific heat of multiferroic CoCr2O4 in magnetic fields up to 14 T. The high-field magnetization measurements indicate a new phase transition at T* = 5 - 6 K. The phase between T* and the lock-in transition at
15 K is characterized by magnetic irreversibility. At higher magnetic fields, the irreversibility increases. Specific-heat measurements confirm the transition at T*, and also show irreversible behavior. We construct a field-temperature phase diagram of CoCr2O4.
A new calorimeter for measurements of the AC heat capacity and magnetocaloric effect of small samples in pulsed magnetic fields is discussed for the exploration of thermal and thermodynamic properties at temperatures down to 2 K. We tested the method
up to mu 0H = 50 Tesla, but it could be extended to higher fields. For these measurements we used carefully calibrated bare chip Cernoxtextregistered and RuO2 thermometers, and we present a comparison of their performance. The monotonic temperature and magnetic field dependences of the magneto resistance of RuO2 allow us to carry on precise thermometry with a precision as good as pm 1mK at T = 2 K. To test the performance of our calorimeter, AC heat capacity and magnetocaloric effect for the spin-dimer compound Sr3Cr2O8 and the triangular lattice antiferromagnet RbFe(MoO4)2 are presented.
We report on a new high resolution apparatus for measuring magnetostriction suitable for use at cryogenic temperatures in pulsed high magnetic fields which we have developed at the Hochfeld-Magnetlabor Dresden. Optical fibre strain gauges based on Fi
bre Bragg Gratings are used to measure the strain in small (~1mm) samples. We describe the implementation of a fast measurement system capable of resolving strains in the order of $10^{-7}$ with a full bandwidth of 47kHz, and demonstrate its use on single crystal samples of GdSb and GdSi.
The electrocaloric effect (ECE), i.e., the reversible temperature change due to the adiabatic variation of the electric field, is of great interest due to its potential technological applications. Based on entropy arguments, we present a new framewor
k to attain giant ECE. Our findings are fourfold: $i$) we employ the recently-proposed electric Gruneisen parameter $Gamma_E$ to quantify the ECE and discuss its advantages over the existing so-called electrocaloric strength; $ii$) prediction of giant caloric effects $close$ to $any$ critical end point; $iii$) proposal of potential key-ingredients to enhance the ECE; $iv$) demonstration of $Gamma_E$ as a proper parameter to probe quantum ferroelectricity in connection with the celebrated Barretts formula. Our findings enable us to interpret the recently-reported large ECE at room-temperature in oxide multilayer capacitors [Nature 575, 468 (2019)], paving thus the way for new venues in the field.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
