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Measurements of Surface Impedance in MgB_{2} in DC Magnetic Fields: Insights in Flux-Flow Resistivity

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## Abstract

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## 1. Introduction

## 2. Surface Resistance in the Mixed State

## 3. Measurement Technique

## 4. Experimental Section

#### 4.1. Sample Preparation

#### 4.2. Surface Resistance

#### 4.3. Vortex Parameters

## 5. Conclusions

## Author Contributions

## Funding

## Data Availability Statement

## Acknowledgments

## Conflicts of Interest

## References

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**Figure 2.**Surface resistance ${R}_{s}$ vs. T measured with different applied magnetic fields ${\mu}_{0}H$ at the frequencies of ${\nu}_{1}=16.5$ GHz in (

**a**) and ${\nu}_{2}=26.7$ GHz in (

**b**). In the inset of (

**a**), the procedure used for the determination of the critical temperature ${T}_{c}$ at different applied fields is shown.

**Figure 3.**${H}_{c2}$ as derived from the surface resistance data of Figure 2, compared to reported data in the literature as measured in polycrystalline samples [53,54] and in single crystals; in the latter case, with the applied magnetic field oriented both parallel to the a–b planes and the c axis. The continuous lines were the fit of anisotropic data, taken from [1]. The data obtained on the polycrystalline sample studied in this work were consistent with the values measured in other polycrystals and fell well between the two limits of ${H}_{c2}$ measured on oriented single crystals.

**Figure 4.**Ratio of the surface resistance measured at ${\nu}_{2}=26.7$ GHz and ${\nu}_{1}=16.5$ GHz, ${r}_{21}={R}_{s2}/{R}_{s1}$ in MgB${}_{2}$ at different applied magnetic fields.

**Figure 5.**Surface resistance ${R}_{s}\left({\nu}_{2}\right)$ vs. ${R}_{s}\left({\nu}_{1}\right)$ with T and B as parameters. In particular, curves wre drawn by varying T, while different curves correspond to distinct B values.

**Figure 6.**${\rho}_{ff}$ vs. H at various T, with fits according to Equation (9) reported as dashed lines.

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**MDPI and ACS Style**

Alimenti, A.; Torokhtii, K.; Vidal García, P.; Silva, E.; Grigoroscuta, M.A.; Badica, P.; Crisan, A.; Pompeo, N. Measurements of Surface Impedance in MgB_{2} in DC Magnetic Fields: Insights in Flux-Flow Resistivity. *Materials* **2023**, *16*, 205.
https://doi.org/10.3390/ma16010205

**AMA Style**

Alimenti A, Torokhtii K, Vidal García P, Silva E, Grigoroscuta MA, Badica P, Crisan A, Pompeo N. Measurements of Surface Impedance in MgB_{2} in DC Magnetic Fields: Insights in Flux-Flow Resistivity. *Materials*. 2023; 16(1):205.
https://doi.org/10.3390/ma16010205

**Chicago/Turabian Style**

Alimenti, Andrea, Kostiantyn Torokhtii, Pablo Vidal García, Enrico Silva, Mihai Alexandru Grigoroscuta, Petre Badica, Adrian Crisan, and Nicola Pompeo. 2023. "Measurements of Surface Impedance in MgB_{2} in DC Magnetic Fields: Insights in Flux-Flow Resistivity" *Materials* 16, no. 1: 205.
https://doi.org/10.3390/ma16010205