Superconductivity in Carbonaceous Sulfur Hydride: Further Analysis of Relation between Published AC Magnetic Susceptibility Data and Measured Raw Data

In arXiv:2111.15017v1 [1], Dias and Salamat posted some of the measured data for ac magnetic susceptibility of carbonaceous sulfur hydride, a material that was reported in Nature 586, 373 (2020) [2] to be a room temperature superconductor. They provided additional measured data in arXiv:2111.15017v2 [3]. Here I provide an analysis of these data. The results of this analysis indicate that the claim of ref. [2] that magnetic susceptibility measurements support the conclusion that the material is a room temperature superconductor is not supported by valid underlying data.

Incompatibility of Published ac Magnetic Susceptibility of a Room Temperature Superconductor with Measured Raw Data

Room temperature superconductivity has recently been reported for a carbonaceous sulfur hydride (CSH) under high pressure by Snider et al [1]. The paper reports sharp drops in magnetic susceptibility as a function of temperature for five different pressures, that are interpreted as signaling a superconducting transition. Here I question the validity and faithfulness of the magnetic susceptibility data presented in the paper by comparison with the measured raw data reported by two of the authors of ref. [2]. This invalidates the assertion of the paper [1] that the susceptibility measurements support the case for superconductivity in this compound.

Beating standard quantum limit via two-axis magnetic susceptibility measurement

We report a metrology scheme which measures magnetic susceptibility of an atomic spin ensemble along the x and z direction and produces parameter estimation with precision beating the standard quantum limit. The atomic ensemble is initialized via one-axis spin squeezing with optimized squeezing time and parameter φ to be estimated is assumed as uniformly distributed between 0 and 2π, while fixed in each estimation. One estimation of φ can be produced with every two magnetic susceptibility data measured along the two axis respectively, which has imprecision scaling (1.43 ± 0.02)/N 0.687±0.003 with respect to the number N of atomic spins. The measurement scheme is easy to implement and is robust against measurement fluctuation caused by environment noise and measurement defects.

Incompatibility of Published ac Magnetic Susceptibility of a Room Temperature Superconductor with Measured Raw Data

Room temperature superconductivity has recently been reported for a carbonaceous sulfur hydride (CSH) under high pressure by Snider et al [1]. The paper reports sharp drops in magnetic susceptibility as a function of temperature for five different pressures, that are interpreted as signaling a superconducting transition. Here I question the validity and faithfulness of the magnetic susceptibility data presented in the paper by comparison with the measured raw data reported by two of the authors of ref. [2]. This casts doubt on the assertion of the paper [1] that the susceptibility measurements support the case for superconductivity in this compound.

Collective Magnetic Behavior of 11 nm Photo-Switchable CsCoFe Prussian Blue Analogue Nanocrystals: Effect of Dilution and Light Intensity

The collective magnetic behavior of photoswitchable 11 nm cyanide-bridged nanoparticles based of the Prussian blue analogue CsCoFe were investigated when embedded in two different matrices with different concentrations. The effect of the intensity of light irradiation was studied in the less concentrated sample. Magnetization studies and alternating magnetic susceptibility data are consistent with a collective magnetic behavior due to interparticle dipolar magnetic interaction for the two compounds, even though the objects have a size that place them in the superparamagnetic regime.

The Effect of Partial Substitution of Non-Magnetic Impurity Zn on the Magnetic Moments of Eu1.88Ce0.12Cu1-yZnyO4+α-δ

Structure and magnetic properties of electron-doped superconducting cuprates have been investigated in order to study the effect of magnetic impurity to its physical properties. Here, we reported structure and magnetic properties of Eu1.88Ce0.12Cu1-yZnyO4+α-δ (ECCZO) with y = 0 and 0.03. The properties of ECCZO have been studied from X-ray diffraction data and temperature dependence of magnetic susceptibility data, to elucidate the effect of partial substitution of non-magnetic impurity Zn for Cu to its structure, Tc and the value of magnetic moments per unit volume extracted from susceptibility data in normal state. Magnetic-susceptibility measurements were carried out down to 2 K on-field cooling at 5 Oe for Eu1.88Ce0.12Cu1-yZnyO4+a-d with y = 0 and 0.03. For ECCZO sample with y = 0 and d = 0.0669 indicated the change of magnetic behavior from paramagnetic to diamagnetic below 12 K which is addressed to the Tc onset of this samples. Diamagnetic behavior is observed starting from about 12 K. Above 12 K, all samples show paramagnetic behavior with the values of the magnetic moment in every volume unit increased with increasing Zn.

Thermodynamics and cooperativeness of the spin crossover

Spin transition – a passage from the low-spin electronic state to the high-spin one of Fe(III) and Fe(II) complexes is assessed from several points of view: theoretical modelling, magnetic susceptibility data, and calorimetric measurements. The concept of the cooperativeness in the solid state is discussed in detail. Thermodynamic parameters are mutually correlated for a set of analogous Fe(III) complexes by using modern statistical methods.