First-order reversal curves analysis of rate-dependent hysteresis: The example of light-induced thermal hysteresis in a spin-crossover solid

2005 ◽  
Vol 72 (5) ◽  
Author(s):  
Cristian Enachescu ◽  
Radu Tanasa ◽  
Alexandru Stancu ◽  
Francois Varret ◽  
Jorge Linares ◽  
...  
Keyword(s):  
Spin Crossover ◽  
Thermal Hysteresis ◽  
First Order ◽  
Rate Dependent

scholarly journals Analysis of first order reversal curves in the thermal hysteresis of spin-crossover nanoparticles within the mechanoelastic model

2015 ◽  
Vol 117 (17) ◽  
pp. 17B307 ◽  
Author(s):  
Laurentiu Stoleriu ◽  
Alexandru Stancu ◽  
Pradip Chakraborty ◽  
Andreas Hauser ◽  
Cristian Enachescu
Keyword(s):  
Spin Crossover ◽  
Thermal Hysteresis ◽  
First Order

scholarly journals Evidence of Photo-Thermal Effects on the First-Order Thermo-Induced Spin Transition of [{Fe(NCSe)(py)2}2(m-bpypz)] Spin-Crossover Material

2019 ◽  
Vol 5 (2) ◽  
pp. 21 ◽  
Author(s):  
Kamel Boukheddaden ◽  
Houcem Fourati ◽  
Yogendra Singh ◽  
Guillaume Chastanet
Keyword(s):  
Thermal Effects ◽  
Spin Crossover ◽  
Evolution Equations ◽  
Thermal Hysteresis ◽  
Magnetic Measurements ◽  
Equations Of Motion ◽  
Spin Transition ◽  
Thermal Bath ◽  
Trapping Region ◽  
First Order

We have investigated by means of optical microscopy and magnetic measurements the first-order thermal spin transition of the [{Fe(NCSe)(py)2}2(m-bpypz)] spin-crossover compound under various shining intensities, far from the light-induced spin-state trapping region. We found evidence of photo-heating effects on the thermally-induced hysteretic response of this spin-crossover material, thus causing the shift of the thermal hysteresis to lower temperature regions. The experimental results are discussed in terms of the apparent crystal temperature and are analyzed theoretically using two evolution equations of motion, written on the high-spin (HS) fraction and heat balance between the crystal and the thermal bath. A very good qualitative agreement was found between experiment and theory in the stationary regime, explaining the experimental observations well and identifying the key factors governing these photo-thermal effects.

scholarly journals Unexpected Light-Induced Thermal Hysteresis in Matrix Embedded Low Cooperative Spin Crossover Microparticles

2021 ◽  
Vol 7 (5) ◽  
pp. 59
Author(s):  
Diana Plesca ◽  
Anastasia Railean ◽  
Radu Tanasa ◽  
Alexandru Stancu ◽  
Jérôme Laisney ◽  
...  
Keyword(s):  
Ground State ◽  
Spin Crossover ◽  
Thermal Hysteresis ◽  
Mean Field ◽  
High Spin State ◽  
Field Approach ◽  
First Order ◽  
External Pressures ◽  
Matrix Interactions ◽  
Spin Ground State

The embedding of spin-crossover micro- or nanocrystals in various surroundings dramatically changes their functionalities based on first-order spin transitions. The dampening of their internal cooperativity, together with introducing a new kind of interactions occurring at interfaces between spin-crossover particles and their environment, results in spectacular effects, as an enhanced hysteresis with non-cooperative transitions. In this work, we deal with the influence of the embedding matrix on the light-induced thermal hysteresis (LITH) in the case of spin-crossover microparticles of Fe(phen)2(NCS)2. Despite the low cooperativity of this compound, the competition between the continuous photoexcitation towards the metastable high spin state and the relaxation down to low spin ground state leads to a light-induced thermal hysteresis, with a quasi-static width of around 10 K. This unexpected hysteresis is explained by considering a switch-on/cutoff mechanism of the particle–matrix interactions in the framework of a mean-field approach based on negative external pressures, with Gaussian distributed variations and of an Ising-like model with various interactions with the environment. Additional first-order reversal curves measurements and corresponding calculated distributions are in line with relaxations under light and confirm the existence of a non-kinetic LITH.

Spin-crossover in an iron(iii) complex showing a broad thermal hysteresis

2021 ◽  
Author(s):  
Cyril Rajnák ◽  
Romana Mičová ◽  
Ján Moncoľ ◽  
Ľubor Dlháň ◽  
Christoph Krüger ◽  
...  
Keyword(s):  
Schiff Base ◽  
Schiff Base Ligand ◽  
Spin Crossover ◽  
Thermal Hysteresis ◽  
Mononuclear Complex ◽  
Hysteresis Width ◽  
Thermally Induced

A pentadentate Schiff-base ligand 3,5Cl-L2− and NCSe− form a iron(iii) mononuclear complex [Fe(3,5Cl-L)(NCSe)], which shows a thermally induced spin crossover with a broad hysteresis width of 24 K between 123 K (warming) and 99 K (cooling).

scholarly journals A graphical solution of a differential equation with application to hill’s treatment of nerve excitation

1937 ◽  
Vol 123 (832) ◽  
pp. 382-395 ◽  
Keyword(s):  
Viscous Medium ◽  
Graphical Solution ◽  
Initial Value ◽  
First Order ◽  
Rate Dependent ◽  
Monomolecular Reaction ◽  
Constant Coefficients ◽  
Linear Differential ◽  
Physical And Chemical ◽  
Nerve Excitation

Linear differential equations with constant coefficients are very common in physical and chemical science, and of these, the simplest and most frequently met is the first-order equation a dy / dt + y = f(t) , (1) where a is a constant, and f(t) a single-valued function of t . The equation signifies that the quantity y is removed at a rate proportional to the amount present at each instant, and is simultaneously restored at a rate dependent only upon the instant in question. Familiar examples of this equation are the charging of a condenser, the course of a monomolecular reaction, the movement of a light body in a viscous medium, etc. The solution of this equation is easily shown to be y = e - t / a { y 0 = 1 / a ∫ t 0 e t /a f(t) dt , (2) where y 0 is the initial value of y . In the case where f(t) = 0, this reduces to the well-known exponential decay of y .

scholarly journals Reversibility of the Magnetocaloric Effect in the Bean-Rodbell Model

2021 ◽  
Vol 7 (5) ◽  
pp. 60
Author(s):  
Luis M. Moreno-Ramírez ◽  
Victorino Franco
Keyword(s):  
Magnetic Field ◽  
Thermal Hysteresis ◽  
Entropy Change ◽  
Second Order ◽  
Zero Field ◽  
First Order ◽  
Magnetic Field Change ◽  
Magnetocaloric Materials ◽  
Moderate Magnetic Field ◽  
The Magnetic Field

The applicability of magnetocaloric materials is limited by irreversibility. In this work, we evaluate the reversible magnetocaloric response associated with magnetoelastic transitions in the framework of the Bean-Rodbell model. This model allows the description of both second- and first-order magnetoelastic transitions by the modification of the η parameter (η<1 for second-order and η>1 for first-order ones). The response is quantified via the Temperature-averaged Entropy Change (TEC), which has been shown to be an easy and effective figure of merit for magnetocaloric materials. A strong magnetic field dependence of TEC is found for first-order transitions, having a significant increase when the magnetic field is large enough to overcome the thermal hysteresis of the material observed at zero field. This field value, as well as the magnetic field evolution of the transition temperature, strongly depend on the atomic magnetic moment of the material. For a moderate magnetic field change of 2 T, first-order transitions with η≈1.3−1.8 have better TEC than those corresponding to stronger first-order transitions and even second-order ones.

Tuning Size and Thermal Hysteresis in Bistable Spin Crossover Nanoparticles

2010 ◽  
Vol 49 (12) ◽  
pp. 5706-5714 ◽  
Author(s):  
José Ramón Galán-Mascarós ◽  
Eugenio Coronado ◽  
Alicia Forment-Aliaga ◽  
María Monrabal-Capilla ◽  
Elena Pinilla-Cienfuegos ◽  
...  
Keyword(s):  
Spin Crossover ◽  
Thermal Hysteresis

First-order reversal curve analysis of spin-transition thermal hysteresis in terms of physical-parameter distributions and their correlations

2005 ◽  
Vol 71 (1) ◽  
Author(s):  
Radu Tanasa ◽  
Cristian Enachescu ◽  
Alexandru Stancu ◽  
Jorge Linares ◽  
Epiphane Codjovi ◽  
...  
Keyword(s):  
Physical Parameter ◽  
Thermal Hysteresis ◽  
Spin Transition ◽  
Curve Analysis ◽  
First Order ◽  
Parameter Distributions
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