diff --git a/ozcan-linear.png b/ozcan-linear.png new file mode 100755 index 0000000..798c431 Binary files /dev/null and b/ozcan-linear.png differ diff --git a/references.bib b/references.bib index 98e57b9..345cb78 100755 --- a/references.bib +++ b/references.bib @@ -165,4 +165,20 @@ Results from previous neutron measurements are found to be consistent with the X month = jun, year = {1993}, pages = {3999--4002}, -} \ No newline at end of file +} + +@article{paglione_quantum_2016, + title = {Quantum {Critical} {Quasiparticle} {Scattering} within the {Superconducting} {State} of {CeCoIn} 5}, + volume = {117}, + issn = {0031-9007, 1079-7114}, + url = {https://link.aps.org/doi/10.1103/PhysRevLett.117.016601}, + doi = {10.1103/PhysRevLett.117.016601}, + language = {en}, + number = {1}, + urldate = {2022-05-18}, + journal = {Physical Review Letters}, + author = {Paglione, Johnpierre and Tanatar, M. A. and Reid, J.-Ph. and Shakeripour, H. and Petrovic, C. and Taillefer, Louis}, + month = jun, + year = {2016}, + pages = {016601}, +} diff --git a/superconductivity_assignment5_kvkempen.pdf b/superconductivity_assignment5_kvkempen.pdf new file mode 100755 index 0000000..98a9c80 Binary files /dev/null and b/superconductivity_assignment5_kvkempen.pdf differ diff --git a/superconductivity_assignment5_kvkempen.tex b/superconductivity_assignment5_kvkempen.tex index 5d81f73..3964f83 100755 --- a/superconductivity_assignment5_kvkempen.tex +++ b/superconductivity_assignment5_kvkempen.tex @@ -212,7 +212,29 @@ They are, however, kept constant, and $\lambda$ is what is varied by changing th With knowledge about $\lambda(0)$ from other sources, $\lambda(T)$ is determined by determining $\Delta \lambda$ from $\delta f$. Now the superfluid density can be determined. +In \cite{ozcan}, heavy-fermion superconductor \ce{CeCoIn5} is investigated using the TDO technique to measure its penetration depth. +It is an unconventional superconductor, and the question is what type of wave-symmetry it exhibits. +The paper found a non-linear $\lambda(T)$ relation. +See figure \ref{fig:linear-lambda} for their results. +They do conclude that the material is in a $d_{x^2-y^2}$ superconductor ground state. +I would expect there to be no nodes in the band gap energy, in this case, which however is the case. +The authors also seem puzzled at the beginning. +They suspect strong-scattering impurities to alter the $\lambda(T)$ relation. +To exclude this possibility, they checked a couple of possible explanations. +Purity was checked and impurity content was determined to be a factor 100 smaller than the deviation in $\lambda(T)$ would imply. +Other theories were also ruled out, on impossibility of far-fetchedness. +They conclude by proposing non-Fermi-liquid renormalisation in both the normal and superconducting state of \ce{CeCoIn5} to take place, yielding the well fitting relation as seen in the inset of figure \ref{fig:linear-lambda}. +This means that their would be quantum criticality in the superconducting state, i.e. a phase transition at zero temperature. +That would be exotic. +In conclusion, the behavior of \ce{CeCoIn5} was not explained with certainty at the point this paper was published (2003), although quantum criticality was a possibility. +However, years later (2014), further research supports their hypothesis \cite{paglione_quantum_2016}. +\begin{figure} + \centering + \includegraphics[width=.6\textwidth]{ozcan-linear.png} + \caption{For \ce{CeCoIn5}, $\lambda(T) \propto T^2/(T-T^*)$ is plotted in the main plot. In the inset, the concluding hypothesis of the authors \cite{ozcan} is presented, i.e. $\lambda(T) \propto T^{1.5}$.} + \label{fig:linear-lambda} +\end{figure} \bibliographystyle{vancouver} \bibliography{references.bib}