SciPost Submission Page
Hole doping and electronic correlations in Cr substituted BaFe2As2
by Marlid dos Reis Cantarino, Kevin R. Pakuszewski, Bjoern Salzmann, Pedro H. A. Moya, Wagner R. da Silva Neto, Gabriel S. Freitas, Pascoal G. Pagliuso, Cris Adriano, Walber H. Brito, Fernando A. Garcia
Submission summary
| Authors (as registered SciPost users): | Marli dos Reis Cantarino |
| Submission information | |
|---|---|
| Preprint Link: | scipost_202405_00013v1 (pdf) |
| Date submitted: | 2024-05-08 12:26 |
| Submitted by: | dos Reis Cantarino, Marli |
| Submitted to: | SciPost Physics |
| Ontological classification | |
|---|---|
| Academic field: | Physics |
| Specialties: |
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| Approaches: | Theoretical, Experimental, Computational |
Abstract
The absence of superconductivity (SC) in Cr-substituted BaFe2As2 (CrBFA) is a well-established but poorly understood topic. It is also established that the suppression of the spin density wave transition temperature (TSDW) in CrBFA and Mn-substituted BaFe2As2 (MnBFA) almost coincides as a function of the Cr/Mn concentrations, irrespective of the putative distinct electronic effects of these substitutions. In this work, we employ angle-resolved photoemission spectroscopy (ARPES) and combined density functional theory plus dynamical mean field theory calculations (DFT+DMFT) to address the evolution of the Fermi surface (FS) and electronic correlations in CrBFA. Our findings reveal that incorporating Cr leads to an effective hole doping of the states near the FS in a way that can be well described within the virtual crystal approximation (VCA). Moreover, our results show orbital-specific correlation effects that support the Hund localization scenario for the CrBFA phase diagram. We found a fractional scaling of the imaginary part of self-energy as a function of the binding energy, which is a signature property of Hund's metals. We conclude that CrBFA is a correlated electron system for which the changes in the FS as a function of Cr are not related to the suppression of TSDW. Rather, this suppression and the absence of SC are primarily due to the competition between Cr local moments and the Fe-derived itinerant spin fluctuations.
Author indications on fulfilling journal expectations
- Provide a novel and synergetic link between different research areas.
- Open a new pathway in an existing or a new research direction, with clear potential for multi-pronged follow-up work
- Detail a groundbreaking theoretical/experimental/computational discovery
- Present a breakthrough on a previously-identified and long-standing research stumbling block
Current status:
Reports on this Submission
Strengths
- Extensive and interesting experimental study supported by theoretical calculations.
- Transparent presentation of the results.
Weaknesses
- Rather technical and lengthy paper.
Report
The submitted manuscript presents an interesting and comprehensive ARPES study of Cr-substituted BaFe2As2. The findings are underlined by DFT+DMFT computations. I believe it is suitable for publication in SciPost Physics, after the authors address the reviewers' requested changes.
Requested changes
1) The manuscript is rather long and some passages are quite technical. I believe that the paper could profit from a broader readership if the authors find a way to present their most important findings in a more succint way, e.g. by moving some of the technical details to an appendix (e.g. the paragraph and corresponding figure regarding the shifted dz2 band on pg.8, …)
2) Besides the VCA DFT+DMFT computations, the authors also present computational results without VCA (e.g. in figure 1e). If I understand correctly, in these computations only the lattice parameters have been adjusted to the ones of the Cr-doped samples? This might not account for all potential changes in hybridisation effects due to the presence of Cr. I think that showing these results without VCA does not add much to the paper (the spectral function in figure 1e looks essentially the same as in fig. 1d, in fig. 4b the experimental results lie in between the theory results with and without VCA, so I would not conclude much from this), while it may confuse less experienced readers. So I would move these figures together with the corresponding discussions to an appendix, maybe entitled ‘Validity and limitation of the theoretical approach’. In the main text it is sufficient to mention that the VCA approximation does not account for all experimentally observed results, as the authors already do mention on pg. 5.
3) My last concern regards some of the conclusions the authors draw from their study. They state that superconductivity is lacking in CrBFA mainly because of the competition between the Cr local moments and the Fe magnetism (pg. 11). While this sounds plausible, it is not something which is directly investigated in their work, but rather a speculation compatible with their results and should also be formulated in that way. Thus, I suggest that also in the conclusions the authors stick more closely to their results and what they can directly conclude or rule out. Furthermore, I am not sure if the suggested breakdown of low-energy effective models (pg. 11) is a plausible conclusion. Wouldn’t a higher level of theory, which can account e.g. for spin fluctuations and magnetism, or investigations at lower temperature, possibly be able to capture the physics of the material, despite concentrating on the low-energy degrees of freedom?
Recommendation
Ask for minor revision
Report 1 by Huiqian Luo on 2024-6-20 (Invited Report)
Strengths
1. Full comparison between ARPES experimental results and theory calculations;
2. High quality data;
3. Clear conclusions;
Weaknesses
1. More analysis on the band renormalization will be better
Report
This manuscript reports a combined study on ARPES and band calculations on Cr doped BaFe2As2, a iron-based compound without superconductivity. It is indeed a puzzle that the Cr doping in the 122 familiy of iron-based superconductors. Most of transition metal dopants, such as Ni, Co, Ir, Rh, Pd, Ru, will induce superconductivity in BaFe2As2, except for Cr and Mn, which suppose to give hole dopings in the system. In fact, there is no hole doped on iron site for all superconducting compounds in 122 family. This manuscript give a possible explanation, while the Cr substitution indeed enlarge the hole pockets, which means hole doping into the system, but the electron pockets do not change much. The absence of superconductivity are primarily due to the competition between Cr local moments and the Fe-derived itinerant spin fluctuations. I believe their analysis and conclusions are solid and worthy to publish on SciPost.
I only have one minor suggestions for their consideration: as they have both DFT+DMFT calculation results and ARPES results, is there possible to give the results of orbital- and momentum-dependent band renormalization, namely the ratio between the effective mass and electron mass. To compare the the band renormalization factors upon Cr doping, will certainly give a clear picture about the electronic correlations in this system.
Requested changes
More discussions on the band width and renormalizations.
Recommendation
Publish (easily meets expectations and criteria for this Journal; among top 50%)