Peer review of: Non-monotonic pressure dependence of high-field nematicity and magnetism in CeRhIn5 (2020)



RR2
REVIEWERS' COMMENTS:
Reviewer #1 (Remarks to the Author):
Report on revised version of manuscript 241006 by T. Helm et al.
   The authors have made relatively few modifications to the manuscript but have incorporated several
 changes that significantly respond to some of the criticisms of the 3 referees.
 Concerning whether the anomaly at B* it is not a question of “belief” (theirs, mine or anyone else’s)
 that this phase is Nematic. What appears dangerous to me is that after initial works that propose this
 solution, which I agree is plausible and perhaps even probable, it should then become an accepted
 truth.
 However the addition of the sentence “For these reasons we shall refer to the sudden and strong field
 induced transport anisotropy at B* as a consequence of nematicity” satisfies me. I would like in
 addition a phrase to the effect of what they write clearly in the rebuttal letter “The main result of this
 paper here is to trace the field scale, B*(p), into the high-pressure regime regardless of its
 microscopic origin”
 I find on the other hand the discussion of the extended Doniach diagram still very muddled. If it is
 only intended as a cartoon perhaps this should be stated more explicitly, because for the moment it
 looks like a model. An extended Doniach diagram should have 2 possible mechanisms: a field
 dependence of J, or different field dependences of TK and TRKKY for a given J, and of course a
 possible combination of both. I had initially assumed that the model was based on the field effect on J.
 According to their rebuttal this is not the case, however it is stated in the text “To extend the zero-
 field Doniach model, the field dependence of the coupling J has to be taken into account (Fig. 7 b), ” .
 However fig 7b implicitly assumes a field independent J (i.e. the magnetic bubble moves to the right
 with field for constant J). This diagram is far from trivial and raises questions. Actually the initial
 increase of Bc where TN increases is trivial. To capture the physics here it is necessary to describe the
 increase of Bc when TN decreases, so it is only in the small right hand part of the diagram. But then
 shouldn't Bc be a function of TK as well as TRKKY (just as TN is) ? Or is it implicitly assumed that the
 Kondo effect is washed out with field but RKKY is unchanged ? But then how do you explain the
 continuity of Jc ?
 The authors should state explicitly what mechanism is in play in their diagram and whether or not this
 can explain all the results. Actually this part seems to me to show that a simple extended Doniach
 picture will have great difficulty capturing the physics in play here. The last part of the discussion is
 much clearer and basically the conclusion is that the explanation must be sought elsewhere. i.e.
 frustration or non trivial field dependence of coupling constants.
 I think the authors have captured all the ingredients that can possibly explain the re-entrance of
 magnetism but it could be presented much more simply and clearly. I leave the editors to decide
 whether the present format is acceptable or whether it should be further improved.
 The 2D figure in the supplement (fig S11) is very clear and useful. It would be nice to make a
 reference to it in the caption of fig7
 I maintain my initial judgment that the high quality of the experimental work and interesting physics
 warrant publication in Nat Comm. While I find that the paper could still be improved, this can now be
 considered optional, depending on editorial decision.

 Reviewer #2 (Remarks to the Author):
Reviewer #3 (Remarks to the Author):
 In the revised version, the authors weakened their major claims. This is fair as we are all aware of the
 versatility and the complexity of this material. For example, very recent NMR measurements further
 confirmed the rotational symmetry breaking of the electronic structure in the AFM3 phase already
 [arxiv:200501421], which should modify the phase diagram of CeRhIn5 and challenge the concluded
 role of magnetism in this work. In addition, given the criterion for the phase boundaries are not robust
 in experimental data, I leave the final judgement up to the editor.
  As I have previously stated, I am strongly support the publication of the manuscript. With the revised
 version and also with their detailed replies to my comments and suggestions, I recommend that the
 manuscript will be published as is. I have also studied the replies and changes in response to the
 remarks of the other referees, and would like to point out that the authors have considered them
 carefully as well. Overall my impression is that the revised version of the manuscript is substantially
 stronger than the already impressive previous manuscript. In conclusion, the impressive methodology
 together with the high quality of the data on a quantum material of current interest clearly deserve to
 be published in Nature Communications. I am convinced that the manuscript will be met with great
 interest by the readers of this journal.