Merge branch 'master' of https://git.overleaf.com/5cf56f861d72e9071d1a343c

1 files changed, 4 insertions, 12 deletions

diff --git a/referee_comments.txt b/referee_comments.txt
index b10b819..87f2116 100644
--- a/referee_comments.txt
+++ b/referee_comments.txt
@@ -78,10 +78,7 @@ referee_response_cutoff_curves.pdf.
 > Is it possible to say something about the c/a ratio, which displays a 
 > non-trivial T-dependence? 
 
-The c/a ratio is governed by the behavior of the A1g moduli, which exhibit no
-novel behavior in our theory. We therefore have nothing to say about it.
-
-[Add something to cite about why we shouldn't need to say something about this?]
+The behaviour of c/a is indeed interesting, but our model only considers the coupling to the two in-plane shear strains, since it is one of these that shows the anomalous behaviour. To talk about the c/a ratio we would have to introduce coupling between the order parameter and the A1g strains (\epsilon_xx + \epsilon_yy, and \epsilon_zz). Because the order parameter we consider breaks both translational and (locally) point-group symmetries, this coupling would be quadratic-in-order-parameter, linear-in-strain, and would thus be generic to any order parameter. Put more simply - our model has special coupling to a particular shear strain, whereas the c/a ratio is related to compresisonal strains, which couples to our order parameter in the same way as it does to any other (non-A_1g) order parameter. 
 
 > At last, I understand that the model is meant to be purely 
 > phenomenological, but given the plethora of publications on URu2Si2 
@@ -118,10 +115,7 @@ This is a consistent with hexadecapolar order
 > within the mean-field treatment and does not provide a novel 
 > theoretical advance. 
 
-[hmmmm what can you say to this. i guess we can emphasize the part you did that IS new, at least we think it's new. Also, what's wrong with using existing, working tools for sovling problem?!?!!!!?!?!?! Does everyone have to come up with some black-hole-based-nonsense every time they solve a problem?]
-
-In addition, the incorporation of gradient terms into the mean-field free
-energy in the context of interpreting ultrasound data appears novel.
+What our manuscript provides is a new way of interpreting a very clear experimental signature - that is, nearly perfect Curie-Weiss 1/(T-T_0) in (c11-c12)/2. We show that a staggered nematic order parameter explains this behaviour. We agree that coupling strains and order parameters is not new, but we do not believe that every scientific advance has to be accompanied by new mathematical machinery for its own sake. Mean-field-theory happens to work quite well here, and allows us to make clear symmetry-based statements. In addition, the incorporation of gradient terms into the mean-field free energy in the context of interpreting ultrasound data appears novel.
 
 > 2) One can generically expect several sources for softening elastic 
 > constants. For example, the authors in ref.25 also succeeded in the 
@@ -129,7 +123,7 @@ energy in the context of interpreting ultrasound data appears novel.
 > T_HO. Thus, the fitting is not regarded as the decisive evidence on 
 > the validity of the model. 
 
-[Not sure how to respond to this; Brad?] [yeah Curie-weiss is generic, that's true. ref 25 is also purely phenomenological (I'm guessing, haven't looked yet), we have testable predictions and connect to other experiments. ]
+There are a couple of very important distinctions to be made between our work and the work of ref. 25 (K.  Kuwahara et al.), which as the referee points out, also identified softening in (c11-c12)/2. First, the data in ref. 25 (figure 2c) appear to be contaminated by the c66 mode, based on the fact that the peak in c66 appears around 60 K. In the work of T. Yanagisawa et al (Journal of the Physical Society of Japan 82 (2013) 013601), the peak is at 130 K, and the elastic constant softens back down to its room-temperature value by T_HO. The data we show in figure 2b, obtained with resonant ultrasound, also shows a maximum at around 130 K, and also softens to its room-temperature value by T_HO. The contamination in ref. 25 is likely an artifact of the pulse-echo ultrasound technique, which can mix between c66 and (c11-c12)/2 when the crystal is not perfectly aligned. Perhaps more importantly, the fit shown in figure 4 of ref 25 does not show very good agreement with the data at any temperature. The model used is one for thermally-populated crystal field levels, and has nothing to do with the phase transition at T_HO. This model does not produce the sharp change in slope of (c11-c12)/2 at T_HO, which is an essential singularity in the thermodynamic free energy and must appear in the elastic moduli, and it does not produce 1/(T-T_0) strain susceptibility above T_HO, which is a signature of strain and order parameter coupling. 
 
 > 3) The agreement of C[B1g] in the region T<T_HO is poor, though only 
 > the cusp at T_HO seems qualitatively consistent with the experiment. 
@@ -173,9 +167,7 @@ transition.
 > The authors do not provide any resolution on that point which is the 
 > most relevant in this problem.
 
-The articles below, also cited in our work, all provide experimental evidence
-for the formation of superlattice structure along the c-axis at ambient
-pressure.
+The articles below, also cited in our work, all provide experimental evidence for the formation of superlattice structure along the c-axis at ambient pressure.
 
 [I pulled these from our citation on the estimate for q_*. Do they actually
 provide the evidence we need? Can someone who knows more about these techniques